Infinity Field HD, a space shooter from Forzefield Studios, has been updated with extensive Joypad support. Joypad is a separate app that allows gamers to control supported games on an iPad or Mac from their iPhone, turning it into a wireless virtual controller with a configurable set of buttons.
That's pretty cool. I'd love to see more games like that. Combine it with outputting the game to the TV via AirPlay and you've got yourself a mini-console there