Update : Ultrasn0w 1.2.4 has been released for more details - Click Here
Unlock iPhone 4, 3GS on iOS 5 with ultrasn0w is coming soon. MuscleNerd of iPhone Dev-team has announced on his Twitter account that any user who is running iOS 4.x.x or lower where ultrasn0w is work will be able to unlock his iPhone 4 or iPhone 3GS on iOS 5 after the Dev-team makes some updates on ultrasn0w.
This is not a new unlock for higher basbands. Ultrasn0w will be updated to work with iOS 5 to unlock the already unlockable basebands.
01.59.00 / 04.26.08 / 05.11.07 / 05.12.01 / 05.13.04 / 06.15.00
Unsupported basebands :
02.10.04 / 03.10.01 / 04.10.01 / 05.14.02 / 05.15.04 / 05.16.02
So the dev-team will release iOS 5 unlock with ultrasn0w soon according to MuscleNerd, stay tuned.
Update: Now you can make iPhone official factory unlock, you can check the details from here