iPhone OS v3.0.1 is out. So far jailbreaking works if you use dev team tools redsn0w and even ultrasn0w. Purplera1n fails. I would recommend holding off the update though. It will not offer you much, if anything, and the current jailbreak state will most likely result in a 3.0 kernel on 3.0.1. In a few days a real jailbreak tool will be released. For those of you that can’t resist, you can update and jailbreak using the guides on this site. Just point redsn0w to your 30 firmware. This works for 2g, 3g, and 3gs.

Not recommended at this time. Good news that Apple hasn’t cracked down on the 3gs hole yet.