The iPhone Dev-Team has updated the RedSn0w 0.9.5 b5-3 to jailbreak iOS 4.0 final on iPhone 3G and iPod Touch 2G. The The Redsn0w 0.9.5 b5-3 also has the ability to hacktivate iPhone 3G iOS 4.0 final. First download RedSn0w 0.9.5 b5-3 and firmware and then follow the steps demonstrated in the video to jailbreak your iPhone 3G or iPod Touch 2G.
Download for RedSn0w 0.9.5 WINDOWS & MAC:
http://sites.google.com/a/iphone-dev.com/files/home
Download the OFFICIAL 4.0 firmware(iOS4) for iPhone 3G here:
http://www.megaupload.com/?d=TWV0BL0E
Download the OFFICIAL 4.0 firmware(iOS4) for iPod Touch 2G here:
http://www.megaupload.com/?d=UH6J3YMG