After the release of Pwnage Tool for Mac users to jailbreak iPhone 2.0 firmware and iPhone 3G, Winpwn 2.0 has been releases to unlock iPhone for Windows users. It can easily unlock/jailbreak iPhone 2.0, iPod Touch 2.0 and iPhone 3G.
The main Features of WinPwn are :

Support for both 1.1.4 and 2.0
Custom Image Support
Custom Payload [...]