Patch 4.0.3 (undocumented changes)

Game Engine

 * Cinematics are now downloaded through the streaming client, making them available to users with digital downloads.

PvP

 * Wintergrasp now utilizes a population balancing system of a 1:1 ratio. Because of this, Tenacity should no longer apply to players during the battle.
 * When queuing for a battleground as a group and a player is unable to join the queue, an error message tells you specifically the name of that player.

User Interface

 * Sound Channels in the Sound & Voice menu is now a drop-down menu rather than a slider.
 * The API UnitDetailedThreatSituation returns 0 threat for effects like Mirror Image or Fade instead of the real threat value.
 * Cold Weather Flying and Flight Master's License now display in the spellbook, along with at which level they are learned. (Flight Master's License isn't learnable without the Cataclysm expansion.)

Bug fixes

 * Fixed Real ID names spelling in friend list in russian localization (names in edit box remains bugged)
 * Fixed display item tooltip issue (PvP items are no longer displayed as requiring Arena Team Rating if they don't)
 * Ghost Gryphons fly with full speed once again.
 * Rewards for completing normal and Heroic Wrath of the Lich King dungeons are properly displayed:
 * 12 Justice Points for a Random Lich King Dungeon
 * 23 Justice Points for a Random Lich King Heroic
 * Frost mages can no longer rename their summoned water elementals.
 * The loot chests in Trial of the Champion now have proper collision models.
 * Tauren Miners get the same XP from Mining as other races. Previously they got less or no XP, compared to others.