PwnageTool is useful for users who want to jailbreak and also unlock their iPhone as it allows users to update their iPhone with a pre-jailbroken iOS firmware while preserving the baseband so that it can be unlocked.
PwnageTool is even more eagerly awaited currently as the baseband that’s included in iOS 4.1 cannot be unlocked.
iPhone 4 users can also use Tiny Umbrella if they want to upgrade to iOS 4.1 to preserve the baseband so that they can unlock it using Ultrasn0w after jailbreaking their iPhone using limera1n or greenpois0n. iPhone 3GS and iPhone 3G users please be careful, Tiny Umbrella does not support this feature for your iPhone.
You can checkout the video of an iPad on iOS 3.2.2 upgraded to a pre-jailbroken iOS 4.1 created using PwnageTool:
iPhone Dev Team is expected to release PwnageTool for iOS 4.1 for iPhone and iPod Touch and iOS 3.2.2 for iPad on Sunday. PwnageTool is available only for Mac users. iH8sn0w, developer of Sn0wbreeze, which is the Windows version of the PwnageTool has also announced that he will be releasing a new version of Sn0wbreeze that makes use of the limera1n exploit after PwnageTool for Mac is released.