I hope they bring back the "double tap to bring up the volume slider" option that 3.0 killed. Seriously, if you have a 1G iPod touch, it's nearly impossible to change the volume of a game unless you exit, enter Music, play a song, change the volume, pause the song, exit music, relaunch the game.
I'm not one to hate Apple, but I was really pissed off about this omission. Not even a menu option for "1G mode".