The final content patch for this expansion, Hour of Twilight, will be available today!  Blizzard has posted a video patch preview for your viewing pleasure: http://www.youtube.com/watch?feature=player_embedded&v=2yz4ebjZCPg

This is a massive content patch with a ton of class and talent changes, new dungeons and raid, etc.  Check out the official release notes for full details: http://us.battle.net/wow/en/blog/3964563/Hour_of_Twilight_Patch_43_Notes-11_29_2011