Game Center is (finally!) coming to iPhones in iOS 4.1. It bears the new, greener look we saw back in July and, as Steve Jobs noted, has a heavy focus on multiplayer. Beyond playing games with friends, there are matchmaking and leaderboards across multiple games; it's more or less Steam for your phone.
Jobs says iOS 4.1 - and thusly, Game Center -- will be arriving "next week," though it won't be arriving on iPad until iOS 4.2 in November. We'll be getting our Canabalt scores as high as possible before next week.