The 3.0.1 update of iPhone OS clearly hasn't changed a lot of things in the system. Indeed, RedSn0w is alreaday able to jailbreak the 3.0.1, without having been updated by the Dev-Team.
You juste have to install the 3.0.1, and then launch RedSn0w and follow the instructions, providing a 3.0 IPSW file (and not the 3.0.1 one, which will not be recognized).