iPhone 3G and 3GS Get iOS 4.2.1. Unlock Via Redsn0w
You waiting is over, as the unlock for iPhone 3G and 3GS units with iOS 4.2.1 on board is here, thanks to the folks of iPhone Dev Team and the famous developer MusclerNerd. A new version of PwnageTool was also released, using the 6.15.00 baseband from the iPad firmware 3.2.2, that runs perfectly on both phones.
The reason for this compatibility is the fact that the iPad and the iPhone 3G/3GS use the same Infineon radio chip. There are a bunch of risks associated with this hack, like the lack of support to reverting back from the baseband 6.15 or ever performing a full restore. Also, if you’re using redsn0w for OSX and Windows, remember that having an old bootrom iPhone 3GS and it’s already unlockable, but you need the iOS 4.2.1 version, you should wait for the release of the unofficial bundle.
The same goes for folks using the PwnageTool, available for now only on OSX. An iPhone 4 version of this unlock tool should be made available soon and you should check out the iPhone Dev team blog, for instructions.