[iphoneunlocker]

Not even a week after iOS 4.2.1 was released, and following the update of the RedSn0w jailbreak, the Dev Team delivered today an update to their UltraSn0w unlock for iOS 4.2.1.

This unlock will work for the iPhone 3G or iPhone 3GS with baseband 04.26.08, 05.11.07, 05.12.01, or 05.13.04. It will also work with iPhone 4 with baseband 01.59.00

for more information go to
UltraSn0w iPhone Unlock for iOS 4.2.1 is Available Iphone Unlock Jailbreak Downloads Activate Hack Tools Application Games - Iphone Downloads For You

[TampaDude]

ultrasn0w 1.2 is out now...

Unlock 4.2.1 iOS on iPhone 3GS / 3G with Ultrasn0w 1.2 [Guide] | Redmond Pie

[Mella]

Currently Mac user can only take advantage of this Unlock as PwnageTool is only for Mac. But, the iPhone Dev Team started working on implementing this into Redsn0w for Windows users. So, stay tuned.