WoW Insider's published an exhaustive guide to World of Warcraft's patch 3.1, which has now gone live on the game's test realms.
There's an insane amount of information through there, but some of the main changes are as follows:
- Mounts will not dismount in water
- Dual specs
- The Ulduar raid instance
- BG queuing now allowed anywhere in the world
Doesn't look as though you're going to be waiting too long for this to go live.