Let's face facts: The iPad is not simply a plus-sized iPod Touch. To run your existing apps, the iPad will either display them at original size in a tiny window or it will scale them up at "2x" resolution to fill the 9.7-in. screen. Neither is certain to make App Store games intrinsically bigger, better experiences. Some apps are still best kept in your pocket.
But a 9.7-in. touch screen is also much more than a few extra inches. It's a qualitatively new way of handling, seeing and playing games - a new medium. These are the games I think will change noticeably on the iPad.