Apple has confirmed via a graphic on its Game Center web page that the iPhone 3G will not support the upcoming social gaming network. The graphic indicates that Game Center will be supported on the iPhone 4, iPhone 3G, and second-, third-, and fourth-generation iPod touch. Mac Rumors notes that in its iOS 4.1 betas, Apple had initially offered support for Game Center on all iOS 4-capable devices, but removed support for the iPhone 3G and second-generation…