The newly released 0.9.2958 versions of WinterBoard and MobileSubstrate, which have been upgraded to supportARM7/Thumb2, should now work on the iPhone 3GS.
Saurik, the developer, has said to upgrade even if you don’t have a 3GS as it includes bug fixes.
ultrasn0w 0.8 has been released today and is now fully working on the 3Gs.
The main 3GS ultrasn0w glitch on hacktivated devices is: need to do Settings->General->Reset->Reset Network settings once.
They have said that stability should be drastically improved for unltrasn0w on the 3GS, for some people however it may take up to 75 seconds after reboot.
To get ultrasn0w 0.8 add http://repo666.ultrasn0w.com/ to your sources.
The Dev-Team have released there official jailbreak tool for all 3.0+ iDevices today and it’s compatible with the iPhone 3GS.
It’s available for Windows, Mac OS X and Linux.
Click here to download the Torrent.