The iPhone Dev Team member MuscleNerd, replied to one of his follower on twitter and confirms that ultrasn0w can unlock iPhone 3GS and iPhone 3G on iOS 4.1 and iOS 4.2 with 05.14.02 baseband and it will be available with in two days after the release of iOS 4.2 to public.
simplysaru: @MuscleNerd thanks.. how long would the wait be for 4.2 any approximate time
MuscleNerd: @simplysaru if you’re on 3G or 3GS, just a day or 2 at most after 4.2 is public (just iPhone enough time to verify stuff)
iPhone 4 has different OS baseband than others and that’s why dev takes a little more time to figure out unlock for iPhone 4 with 2.10.04 baseband on iOS 4.1 and iOS 4.2.
News: Apple is expected to release iOS 4.2 sometime in November this year.