Redsn0w 0.8 tool to jailbreak iPhone 3GS (OS 3.0 firmware) has been released and is available for download. Earlier Dev Team decided not to release the JailBreak for iPhone 3GS iBoot-family until iPhone OS 3.0.1 firmware is out. Last week George Hotz released Purplera1n (beta) tool to Jailbreak iPhone 3GS running on iPhone 3.0 firmware. iPhone Dev team has released Redsn0w 0.8 including the support for iPhone 3GS 3.0 jailbreak.
Redsn0w 0.8 will enable many different add-ons and themes that was not possible with earlier versions of Redsn0w. Redsn0w 0.8 is now available for download for Windows, Mac as well as Linux support too. It is important to note that the updates to ultrasn0w, MobileSubstrate, and WinterBoard are all handled directly through Cydia (after you’ve jailbroken!)
After jailbreaking your iPhone 3GS, Unlock Your iPhone 3GS OS 3.0 With UltraSn0w. Ultrasn0w is also updated to 0.8 to unlock iPhone 3GS. After unlocking with Ultrasn0w on 3GS you need to reset your network settings (Settings->General->Reset->Reset Network settings).
Download Redsn0w 0.8 to Jailbreak iPhone 3GS 3.0