PwnageTool 4.1.3 Unlock Download Available
PwnageTool 4.1.3 has just been released and includes the ability to unlock iPhone 3G and 3GS with basebands later than 05.13.04 (iPhone 4 is apparently in the works). To do this, you will need to jailbreak using PwnageTool and then download Ultrasn0w for iOS 4.2.1 from Cydia. PwnageTool Unlock Edition works by using the iPad 3.2.2 IPSW file on basebands 05.14 and 05.15, this process is not reversible.
The iPhone Dev Team says that iPhone 3GS users with older bootrom should not use PwnageTool if they want to update to iOS 4.2.1, instead they should use the upcoming redsn0w release to update baseband firmware.
Download PwnageTool 4.1.3 Unlock Edition
You can grab the torrent here or use one of the following download mirrors provided by the Dev Team:
PwnageTool runs on Mac OS X. There is no PwnageTool for Windows, instead Windows users will want to download redsn0w 0.9.6b5 instead.
If you are not sure what to do, you can learn how to unlock iOS 4.2.1 for iPhone 3GS and iPhone 3G with ultrasn0w, the unlock does carry some risks for certain baseband versions, since the iPad firmware based unlock is not reversible.
Update: the iPhone Dev Team attached the wrong bundle for iPhone 3GS users with PwnageTool 4.1.3, you can fix this rather easily. Here is what they say about this: Read more »