Unlock iPhone 3Gs and iPhone 4 on iOS 6.1 using Ultrasn0w 1.2.8

                                                      
Ultrasn0w 1.2.8 has just been released for compatibility with iPhone 3Gs and iPhone 4 running iOS 6.1. 
Once again, this update only adds 6.1 compatibility, it does not add compatibility for any of the newer baseband revisions. If you have an iPhone 4, this will only work if you have the 01.59.00 baseband. If you have an iPhone 3Gs, it will work on any of these basebands:
04.26.08, 
05.11.07, 
05.12.01, 
05.13.04 and 
06.15.00. 
If you have a 3Gs that has a newer baseband, you can install the 06.15.00 iPad baseband and then downgrade from 06.15.00 to 05.13.04 using Redsn0w.