When you consider that relatively imprecise controls often tend to limit what kind of games can be played on an iPad, surely the increased surface size, and the amount of functions now being applied, could result in new, innovative ways to play. Imagine an RTS where you can grab, control and manoeuvre units quickly and efficiently - or a puzzle game like Echochrome that allows you to manipulate shapes to solve problems.
In my experience multi-touch seems really underused. The only example I can think of is Cut the Rope, which allows you to cut two sets of ropes simutaneously, but that's simple, common sense stuff.
Isn't there a developer out there that can blow my mind via multi-touch?