Quick heads-up! The latest tweet from Musclenerd suggests that Dev team is already working on a new tool that will allow you to downgrade the iPhone Baseband. Suppose you have an iPhone 4 on iOS 4.1 with baseband 02.10.04; this mystery tool will downgrade its baseband and will allow you to later unlock it using ultrasn0w.
@Jadeye_hu the ultimate (future) goal is to use 06.15 as a stepping stone on the way back *down* to 05.13 via downgrade hack
It would mean a permanent unlock regardless what baseband version for all iPhone 3GS, 3G and iPhone 4 devices. Possibly “iPhone 5″ as well. The challenge to hack the baseband will only be worked upon after releasing much awaited iPhone 4 unlock on baseband 3.10.01 and 2.10.04. We will update you once more information comes-in.