If you were even contemplating jailbreaking your iPad, you're about to be instantly swayed.  After you've jailbroken both your iPad and iPhone/iPod Touch, follow these instructions for the source and device setup.  If you've got some friends with iPhones, SNES (HD) supports up to four controllers at once.  Relive your Super Nintendo glory days with this $700+ setup.  Now if you'll excuse me, I've got some jailbreaking to do.