First I noticed the changes to the mail system. You can now attach up to seven items to a mail message, making my use of the CT Mail Mod obsolete. Also, when you hover over the mail icon now, it tells you who has sent you that letter waiting for you in the mailbox. I know the new hover icons with NPCs were already on the PTR, but their addition to the game makes navigating cities a delight. Each icon tells you instantly who has a quest, who can repair, and who just wants to chat.
I also ran across some interesting things while running through my quests in Dustwallow Marsh. First, quest items laying around in the environment now sparkle to let you know where they are. This is super handy for searching through ship wreckage, for instance. Also, when killing mobs in a group, when you hover over the corpse it will tell you who can loot the corpse. It's a small refinement, but it made collection quests in a group substantially easier.
As I spent my a good amount of my time cruising around on my Flying Reindeer in Shattrath (huzzah for the ability to use Preserved Holly on flying mounts now, I knew I was saving that stuff for a reason) I didn't exactly get to experience a huge amount of game play last night. Have you found anything new since the patch went live that hasn't been mentioned anywhere? Upside down flying Draenei perhaps?