Apparently you haven't been paying attention. There isn't a jailbreak for a 3GS ONLY. Every other iPhone model and the Touch models are jailbroken. I have a 3G on 3.1.3 and I did a jailbreak with it a week ago with Blackra1n. It works just fine. I have SBSettings, MyWi, Intelliscreen, and Backgrounder on it.