Today iOS 4 was released and soon after the iPhone Dev Team released an unlock for iPhone 2G, iPhone 3G, and iPhone 3GS (and possibly iPhone 4).
This unlock supports all basbands 04.26.08 thru 05.13.04, which means all basebands released firmware 3.0 thru 4.0. Though the unlock can only be installed though a jailbreak and an iOS 4.0 jailbreak is yet to be released.
How to Unlock
- Open Cydia, tap on the Manage tab, Sources, Edit, and Add.
- Type in "repo666.ultrasn0w.com" and tap Add Source.
- In the Search tab, type in "ultrasn0w" and install it.