MuscleNerd of iPhone Dev Team has just released an updated version of Redsn0w that improves iPhone 3GS 06.15.00 baseband downgrade which was originally released last month. In case you don’t already know, Redsn0w now allows iPhone 3G and iPhone 3GS users sporting iPad’s 06.15.00 baseband to downgrade back to 05.13.04 baseband with a fully working unlock and GPS.

Jay Freeman (Saurik), the developer behind the infamous Cydia store for iPhone has found a way to downgrade iPhone 3GS from firmware 3.1 to firmware 3.0. This process will only work for those who have saved their SHSH to Cydia Server, for more on SHSH, read the complete detail blog post by Saurik here. Also to note here is that while this method will help you downgrade your firmware from 3.1 to 3.0, your baseband will not be downgraded which means you cant unlock it for now.