Dunno if this counts as the ui they're talkin about, but i guess in a way it does. if they could make it possible to resize the new login screen. i run at 1280x1024 and i want the new login to fill the screen and not be a 800x600 size box in the middle.
also maybe animated buttons and buff icons. nicer looking icons for items in inventory, the ability to change them and such. thats all i can think of atm