Windows 7 Tip: 
YellowSn0w is out and it’s ready to rock. Yellowsn0w 0.9.4 iPhone 3G Soft Unlock Tool – Attempt to unlock iPhone 2G or iPhone 3G with firmware OS version 2.2. Remember, this tool will only work with iPhone 3G firmware 2.2 baseband 02.28.0 and not with any previous ones.
See Also: Download QuickPwn 2.2 to Unlock iPhone & iPhone Touch
Download iPhone and iPod Touch Firmware 2.2 form here
You can download Yellowsn0w from the following two sources.
Cyndia Source: http://apt9.yellowsn0w.com/
Installer repo: http://i.yellowsn0w.com/
thank you