I doubt many full priced games will sell well on it. I was looking up all different games and apps the other day, and oh my god there are so many stupid, pointless, cheap games. :P I got a few cool free ones, but I sure as hell wouldn't pay for a game on it unless I heard from others that it was good.
I bet the iPhone and iPod Touch are going to get pretty nice software sales, but keep in mind that almost every game is less than 5 bucks. Most of them I saw were 99 cents, $1.99, or free.