If you are somebody who has inadvertently upgraded to the new iOS 4.2 update without realizing that it could break your unlock, here is some good news. The upcoming UltraSn0w unlocking application is expected to cover all the basebands – including the recent 05.15.04 that was shipped with iOS 4.2.1.
ssstephD: @MuscleNerd will the new ultrasn0w unlock be able to unl0ck baseband 5.15.04? made the big mistake of upgrading it =/ !
MuscleNerd: @ssstephD it covers 05.15.04 too — but yeah, really need to stay vigilant about not updating 🙁
Since the new UltraSn0w update would cover the latest baseband, it effectively means all basebands shall be covered since the software has already been able to achieve unlock on all the older basebands. UltraSn0w is expected to launch by tomorrow.