iOS 4.2.1/4.1 unlock for iPhone 3GS and iPhone 3G will drop by Sunday, 28th November, according to MuscleNerd. UltraSn0w will unlock iPhone 3GS/3G on iOS 4.2.1/4.1 on Sunday, however, iPhone 4 unlock will take little longer.
According to Musclenerd:
Good progress today…everything is on track for updated ultrasn0w by Sunday/Funday at the latest (longer for iPhone4!)
This, indeed, is a great news for all those who have updated to iOS 4.2.1 and waiting for an unlock solution. iOS 4.2.1 has already been jailbroken with RedSn0w 0.9.6b4 and now the jailbreak community is eagerly waiting for the UltraSn0w update.