Okay, maybe it isn't really an undocumented feature, but I skimmed a load of threads here and none of them mentioned it: If you're listening to music, you can now run an app at the sam time! Before--for me at least--the music would always cut off if I was using the iPod app and decided to play a game of Tris or whatever. On my subway ride home, I wound up listening to Superchunk while I played a few games of Hold 'Em, and being able to do so completely caught me by surprise. And man, was it ever fun.