Loktar_Sun has discovered a new method for unlocking the iPhone, according to a report posted by Laforet.
The method uses Sam Bingner's SAM (Subscriber Artificial Module) package that can be installed on jailbroken phones.
It has been confirmed working by iPhone Dev-Team member MuscleNerd who notes an update may be coming to SAM from @sbingner to make the procedure simpler.
Loktar_Sun's method will work to unlock your iPhone 4S, iPhone 4, iPhone 3GS, or iPhone 3G. We've posted detailed step by step instructions on how to unlock your device here