Blizzcast 3 Summary

Quote from Blizzard staff

General
-PvP armor will be different from the PvE armor entirely in looks and colors this time.
-Daily quests will be more widely used in Wrath of the Lich King and should be in place as soon as the expansion ships. More quests will be available with more randomization to make them less repetitive.

Dungeons
-Wrath of the Lich King should have about a dozen of 5-man dungeons available.
-The loot will be better in Heroic instances.
-The attunement process for both Heroic and raid instances will be improved.
-More timed events will be added in WotLK and they will be tuned to let skilled players really show off that little extra emphasis that they put on raiding.
-Timed runs won't really feel like a necessity anymore, the plan is to make them more like an additional challenge to the dungeon.
-Heroic Badges will be back in WotLK, and the concept will be applied to both Heroic and Raid dungeons. The current plan is to create different Badges for different tiers of gear and just not let players buy all the gear with the same currency.
-Some of the Badge rewards might be spread to reputation vendors as well
-In Utgarde Keep, the first dungeon players will explore, developpers try to vary up the architecture from room to room so it feels and look a little bit different, different creatures are used in the different rooms. Various crowd control types can be used throughout the instances, so the dragons can be hibernated, there is humanoids, undead for the different crowd control types all have options in the dungeon. There are also some really cool scripted boss fights too.

Raids
-25-man gear quality will be 1 tier higher than the one you can find in the 10-man version of the same dungeon.
-10-man and 25-man versions of Armor Sets will use the same models but with different colors or more particle effects for the 25-man version.
-The goal is to keep as many raid timers as possible on a 7 day reset. These timers will always match between 10 and 25-man versions.
-First raids in WotLK will be a little bit more accessible to people in general.
-10/25 man versions of the same instance will have totally separate progression and will be equally hard. The 10-man version isn't supposed to be easier or anything like that.
-With CoT: Culling of Stratholme, the developpers are trying to stay as close as possible from the Warcraft 3 storyline without just recreating the mission in the original game. The whole gameplay have to be changed to make it exciting in a MMO. The Infinite Dragonflight storyline will also be continued here.

Naxxramas / Ashbringer
-Naxxramas is supposed to be an accessible early tier raid which will actually be pretty easy for both 10 and 25 person groups
-The story of Ashbringer will be continued in Wrath of the Lich King
-Whether or not Atiesh exists in its current form or a new form is still undecided.
-Some encounters like the 4 Horsemen, Gothik, Kel'thuzad, and Gluth will definitely have to be changed slightly to fit the new raid sizes.
-The new version will also let developers work again on "flawed" encounters and improves them, -The 4 Horsemen is probably the most important one but developpers think they can also do a better job on Loatheb or Grobbulus.