Apple today confirmed that the Game Center for the iOS will not be supported by the iPhone 3G and second-generation iPod Touches. The multiplayer and social networking tool features a friends system, achievements and leaderboards.

This was revealed to those in the iPhone Developer Program for the third beta of iOS 4.1.  Game Center will still be available on iPhone 3GS, iPhone 4, the latest iPod Touch, and the iPad.

Source: Engadget