Edit: Since the thread got made, time to post some useful info.
Taken from Cairenn's
Press Tour thread.
UI Changes- Addition of scenarios windows
- Addition of challenges windows
- Addition of per-player loot windows
- Addition of bonus loot roll windows
- Addition of black market windows
- Auctions by NPCs of rare items for players to bid on.
- Addition of pet battles windows
- Updated talents windows
- Updated specializations windows
- Updated class mechanics windows
- Updated consolidated buffs display
- The basic display of buffs and debuffs will not change, but the consolidated buffs window is completely different. It will only show in groups (party/raid) and will just show the 8 group buff types you should have
- Updated loot roll box
- Updated character create windows
- Updated auction house windows