The iPhone Dev-Team has released UltraSn0w 1.25 which brings iOS 5.0.1 support to the unlock for older compartible basebands.
iPhone Dev Team’s iPhone 4, 3G, and 3GS software unlock, now with added PwnApple. Compatible with iPhone 4 baseband 01.59.00 and iPhone 3G/3GS basebands 04.26.08, 05.11.07, 05.12.01, 05.13.04 and 06.15.00! Thanks to @sherif_hashim and @Oranav for contributing baseband crashes
If you have one of the supported basebands and wish to update to iOS 5.0.1 you will need to do so with a custom ipsw that doesn’t update your baseband.