Sn0wbreeze 2.3b4 supports Ultrasn0w unlock for basebands (01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00)
Ultrasn0w is NOT compatible with the following basebands! (02.10.04 / 03.10.01 / 04.10.01 / 05.14.02 / 05.15.04)
Upgrading your iPhone 3GS baseband to the 06.15.00 iPad baseband hack to unlock MAY cause you to lose your GPS!
Sn0wbreeze is a tethered iOS 4.3 jailbreak for iPhone, iPad and iPod touch.