The iPhone Dev-Team has released an update to their UltraSn0w unlock bringing support for iOS 5. Remember that NO new basebands are supported in this release. It only adds support for iOS 5 with old basebands.
Here is the list of supported basebands:
- iPhone 4: 01.59.00
- iPhone 3G/3GS: 04.26.08, 05.11.07, 05.12.01, 05.13.04, 06.15.00.
If have one of the above baseband version and need unlock you can upgrade to iOS 5 without updating your baseband using RedSn0w 0.9.9b5.