The Dev-Team is on the ball again and almost ready to release ultrasn0w, the newest version of yellowsn0w! Ultrasn0w is set to work on the newer baseband, 4.26.08, so if you had accidently upgraded you won’t have to worry. The demo of the unlock is shown in the video above.
It is still unsure if the iPhone 3G S will still be jailbreakable by the same methods as previous models, but it is likely. Assuming the iPhone 3G S is jailbreakable, you would be able to use ultrasn0w to unlock your new iPhone 3G S for other carriers.
Either way the Dev-Team is currently testing and fine tuning their Pwnage and Quickpwn tools so that they can be released shortly after the firmware update. According to their website, only ultrasn0w will take until Friday to be released.