The much anticipated iPhone 4 ultrasn0w carrier unlock has just been released by the iPhone Dev-Team. The version of this ultrasnow is 1.0-1. You can find it in Cydia by simply searching for it on jailbroken devices. If you cant find it on search, then just add repo666.ultrasn0w.com (it’s utlrasn0w with a zero not O) repository in Cydia. It works with baseband 01.59 and 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01 and 05.13.04.
If you don’t know why we there’s an unlock for iPhone here’s the reason: it is for enabling your iPhone to work on any other network other then AT&T. After unlocking your iPhone, you can use it with other carrier networks. Talking about other networks, T-Mobile still does not support 3G for iPhone users in USA, so make sure you disable 3G in the network settings of your iPhone before unlocking.