More information has surfaced to the web regarding the second WoW expansion: Wrath of the Lich King. Here's a compilation of known facts so far:

*Note* be sure to also check out the new screenshots and trailer featuring the zones of Lich King.

World

• Northrend is Huge. It is larger than Outland by a couple of zones, and some of the zones in Northrend are bigger than the largest zone in Outland.
• The mounts available to buy in Wrath will probably be able to take passengers. These mounts will also work in the old world (Provided they are land mounts), so players can give low-level characters a ride! The new mounts will also be slightly faster, around the speed of the Armored Netherdrakes.
• We're not sure if that will be available from the start but one of the ideas is to give the players new mounts they can buy and allow these new mounts to be available for passengers.
• Trainers and Auction houses will remain in the "Old World"
• Dalaran wil be in Nothern/Central Northrend, near the final zones
• The Ashbringer lore will feature heavily in Wrath

• Blacksmithing may be able to put Gem slots on items that didn't have them before
• All professions will give players something powerful specific to them, similar to the Epic weapons that weaponsmiths can make just for themselves
• A new metal ore found in Northrend is Cobalt.
• The new cloth in Northrend is called Frostweave.
• The way inscription is going to work is you'll have a series of mats that you need to do and then you'll create a scroll that will actually do the buff of the spell in question. Each scroll will have a specific use, so you won't create a generic scroll, it'll be a special scroll that will upgrade this fireball to do this type of thing. Right now we're still trying to make sure we've got that kind of mechanic down. That's actually most of the work. Most of the work is figuring out how that all works, what the materials are, how that comes together, and once we have that, then figuring out what the individual spells are and what the individual spells are and what the effects are going to be is going to be relatively easy.

• Lake Wintergrasp will have daily quests, and there will probably be a buff that effects the entire continent, as well as rewards from all dungeons similar to the Spirit Shards players can currently get from the Auchindoun instances when their faction controls the area.
• There will probably be two new Arenas in Wrath, one set in Dalaran, one in Orgrimmar Arena

• In Wyrmrest Temple there's a raid instance similar to Onyxia's Lair where it's a small raid instance with a single encounter in the Chamber of Aspects. We plan to put a raid encounter in there and let you take part in that and initially we plan to go with one raid encounter, but if we want to expand the space and introduce other dragon flights we can do that through the Chamber of Aspects.
• A raid encounter in the Nexus will let players free drakes and then fight on their back, allowing them to use their abilities. Bronze, Green, and Red drakes will be available and each one of them will have his own set of abilities. The boss fight is tuned around the abilities of the drakes and players will be able to pick any combination (e.g. 3 Green, 1 Bronze, and 4 Red). There's a boss fight that has lots of adds in it, and one of [the drakes] can apply this buff to a bunch of adds while another one can basically consume the buff and get health back from all of it and also assume a tanking role. So your tank is then healing himself based off of this debuff that another one is applying to everyone.
• Developpers think they didn't reward PvE enough in the Burning Crusade, and will try to change that in WotLK.
• Heroic dungeons weren't rewarding enough in BC, Wrath of the Lich King will change that and make player feel that Heroic instances have their own tier of loot instead of a few additions to the normal loot table. Expanding the Heroic Badge system will be a major step to achieve this.
• The Arthas storyline will play out through the patches as well. So Arthas doesn't die in shipping Wrath of the Lich King. Arthas will die in a content patch.
• PvE ladders on the official armory are possible in the future

• Changing runes won't be as prohibitive as talent speccing or anything like that, but at the same time, it won't be so fluid so that you're doing it between fights. We're going to hit some sweet spot between those two.
• Death Knights aren't restricted to swords, they can also uses maces and axes and dual-wield their 1-hand version. Obviously, they can't use a shield.
• Using a 2-hand weapon or dual-wielding won't change anything to the amount of runes (6) you can use.
• Death Knights will start off in a floating necropolis in the Eastern Plaguelands, much like Naxxramas in its current location. They will then go on to level in a dedicated area East of Tyr's Hand and the Noxious Glade, where they will learn more about the background of Death Knights.
• A few more DK abilities

Blood Presence - DPS. Increases DPS and heals the DK slightly when attacked.
Blood Strike - Does an amount of damage based on how many diseases are on the target.
Blade Strike - Applies disease to the target in addition to doing damage.
Mind Freeze - Interrupts spell casting.

Patch 2.5 ?

• "We just released 2.4.2 on the PTR [public test realm] last week and that's just kind of a minor bug fix patch with a handful of small adjustments. 2.4.0 does represent kind of the last content patch for Burning Crusade and for WoW before Wrath of the Lich King comes out, and so we are talking about doing something in between when 2.4.2 comes out and when Wrath of the Lich King comes out but haven't decided exactly what that is or when that's going to come out. It's only a possibility at this point."
• "There will be no event to open the route to Northrend like AQ; the day of the expansion release, players can go straight into Northrend. However, a month or 2 in advance there will possibly be a large patch, similar to pre TBC. Players will get hints of why they will have to go to Northrend in this peroid, and this patch will possibly feature new talent trees and class changes."
• "Blizzard are planning to bring out cool new items for players to spend all their money on, BEFORE Wrath comes out."

• Inscribers will create glyphs that allow players to modify their spells and abilities.
• Going by the first recipe, which requires Peacebloom, they'll rely on the herbalist gathering profession.
• Every player will get a new spell book page to which they can add six glyphs - currently, four major and two minor.
• Major glyphs will be effective in combat - adding damage over time or stun to a physical attack, for example - while minor glyphs will give convenient or cosmetic improvements, removing the need for some spell reagents.
• Glyphs can be sold at the Auction House.

• Allowing enchanters sell their enchantments at the Auction House is still planned.

• The new vehicle technology, which introduces physics and handling characteristics - including inertia, turning circle, grip and suspension bounce - to land and airborne vehicles and special mounts.
• It also allows for up to eight passengers per vehicle, and brings up bespoke action bars and skills for vehicle and turret operators.
• It was intended to be used solely for PVP siege weapons - Dwarven steam tanks, Forsaken plague spreaders and Orc demolishers.

• Even if you'll be able to meet him as soon as you reach Dragonblight (LVL 71-75), the final encounter against Arthas won't be until the last patch of the Lich King cycle. The Icecrown Citadel, will appear after launch.
• Dragonblight will also let you reunite (violently) with the Scarlet Crusade.
• Players will meet a lot of monsters from Classic WoW in the Grizzly Hills, including Furbolgs, Kobolds, the Venture Company, and Worgen Werewolves.
• Arugal has been resurrected and now leads the Worgen Werewolves in Grizzly Hills.
• In Grizzly Hills, you will also find an evil sister city to the Alliance capital, Ironforge.
• The Argent Dawn faction returns in Zul'Drak.
• In Sholazar Basin, you'll take part in a faction-reputation war between the Wolvar (sentient wolves) and Oracles ("the next evolution of the Murlocs" - a worrying thought). A much lighter take on reputation gaming is promised here, with players actively encouraged to defect to the other side at will.
• The expansion will contain a lot of "vehicle quests" as an evolution of BC's bombing runs - throwing flaming oil at Worgen from horseback, airlifting supplies in a gyrocoptor, and yes, mammoth wrangling.

• All players with a level 55 character will be able to create one Death Knight per realm, per account.
• Blizzard's designers decided to start the class with a full complement of abilities right off the bat, figuring that any player that has advanced a character to level 55 would be able to learn to handle the new class with minimal difficulty.
• Death Knights will have a summonable Skeletal Deatcharger Mount.
• Death Knights aren't using Mana or Energy, the runes are their primary source of power and are slotted into their "blade," which lies underneath their health bar as a visual indicator of what resources are available to the player at any given moment.
• Spent runes automatically refresh after a set period of time, much like a Rogue's energy bar.
• There are six slots in the blade, and the player is free to fill those slots with any given number of Blood, Unholy or Frost runes.
• Death Knights also have a secondary resource called Runic Power generated by using your rune abilities. It will use the same mechanics as rage and increase when you deal damage, or slowly decrease if you're not using it.
• Death Knights will have a lot of abilities that cost all available Runic Power with varying levels of effectiveness based on total Runic Power spent. (Same mechanics as Execute for warriors, or finishing moves for Rogues)
• Death Knights will have spells equivalent to auras called "Presence", providing them with powerful self-buffs depending on their role in the group. (One for tanking, one for damage dealing, etc ...)
• An instant lifedrain spell (described as death coil without the fear component) will be available.
• Death Knights will be the first class to use diseases as a source of damage, with abilities that become strong depending on how many diseases are already applied to the target.
• "Army of the Dead" will spawn numerous undead minions to attack nearby hostiles targets.
• Death Knights will also revive an enemy (or ally) as a ghoul to use it as a pet with its own special abilities like a disease-inflicting strike and a stun.
• When an ally is risen as a ghoul, a pop-up will appear and this ally will have the choice to control the ghoul if he wants to.
• The Death Knight's particular niche will be in tanking magic-damage-dealing bosses. They will have an ability much like a banshee's anti-magic shell, greatly diminishing the amount of incoming magic damage they'll receive in combat

• Death Coil -- Depletes all Runic Power, dealing 600 damage to a non-Undead target, or healing 900 damage on a friendly target.
• Death Grip -- This is the Death Knight's "taunt" ability. It also pulls the target to the Death Knight, forcing them to attack the Death Knight for a short amount of time. Yes, I said pulls the target; Blizzard is going to allow players to move mobs in the expansion both with Death Grip, and other knockback/pull abilities. This works on players too, so PvP balance ahoy!
• Chains of Ice -- Roots the target in place. When the spell fades, it places a snare on the target that reduces in potency as the duration runs out.
• Death Pact -- Sacrifices the raised ghouls to heal the Death Knight.
• Death and Decay -- Targeted, AoE Damage-over-time which pulses similar to the Paladin spell Consecration. Anyone affected by Death and Decay has a chance to be feared.
• Frost Presence -- Increases Armor by 45% and allows the Death Knight to generate 25% more threat. Only one presence can be active at any time.
• Unholy Presence -- Increases Attack Speed and Movement speed by 15%. Only one presence can be active at any time. This was described by Tom Chilton as the "PvP" presence.
• Anti-magic Shield -- Reduces the damage of the next magical spell cast on the Death Knight by 75%. It also converts the damage reduced into Runic Power.
• Strangulate -- Depletes all Runic Power, dealing minor damage and silencing the target for up to 5 seconds.
• Summon Deathcharger -- Allows the Death Knight to summon a Deathcharger mount. This mount is acquired through quests, similar to the Paladin and Warlock land mounts.
• Raise Dead -- Raises a nearby corpse to fight for the Death Knight for 2 minutes. If used on a player corpse, the player has the option to play as the ghoul for the duration -- gaining access to the ghoul's abilities.
  The ghoul has the ability to do the following:
  • Leap to the target
  • Rend for decent damage-over-time
  • Stun target, and of course more

• All raid dungeons in Wrath of the Lich King will have both 10-person and 25-person versions. So at level 80, every major encounter and every big boss fight can be experienced with a group of 10.
• 25-person raiding progression is not dependent on 10-person raiding progression.
• There will be no attunements or keys to obtain, and you won't be locked out of a 25-person instance if you decide to attempt the 10-person version, and vice-versa.
• 25-person raids will earn more, higher-level rewards, in what should be the equivalent of one "tier" of loot quality.
• A new instance focused on the different dragonflights "The Chamber of Aspects" might be added to the game, but this isn't confirmed yet.
• Zero raid bosses have been designed at this point.

• Players will unlock their flying mount at level 77.
• You can use your Outland flying mount, and new flying mounts will be available.