The iPhone Dev team seems to be hard at work since the release of iOS 4. They’ve released their PwnageTool for Mac that allows to jailbreak iPhone 3GS. It also supports jailbreaking of iPhone 3G and iPod touch 2G but users have the option to jailbreak with redsn0w as well.
The jailbreak will allow iPhone 3G / 3GS users to unlock their devices from any baseband with their ultrasn0w tool (downloadable from Cydia) but the team has spelled caution not to update devices blindly so as not to lose the unlocked feature.
The first-gen iPhone and iPod touch as well as iPod touch 3G are not supported yet.
Users can head over to the link below to find the download link of the tool along with instructions on how to jailbreak.