Until now, the iControlPad » 9/01/08 3:30pm 9/01/08 3:30pm was the official-unofficial gamepad add-on for Jailbroken iPhones and iPod Touches. If a leaked advert posted on iPhone games site Touch Arcade is to be believed, though, that may be about to change. The ad shows a device — apparently bearing the Belkin brand name — that looks like a much…