The iPhone Dev-Team has updated RedSn0w 0.9.15 with some bug fixes for iPhone 3GS and iPad owners.
Version 0.9.15b2 fixes a few issues for 3GS owners: old-bootrom awesomeness is no longer forgotten directly after a restore, and iPad baseband upgrade/downgrade support is fixed (same production date cutoffs apply!). If your 3GS is currently tethered at 6.0 even though you have an old bootrom, just re-run redsn0w’s Jailbreak step (no need to restore). Don’t forget you can add some pizzaz with your own boot logo or a nerdy verbose boot.
Redsn0w 0.9.15 brought gives us possibility to do iOS 6 jailbreak and different downgrade options.
The iPhone Dev-Team has announced RedSn0w 0.9.15b1 which brings numerous new features including iOS 6 jailbreak for old devices, ability to restore to older firmware, manipulating SHSH blobs and etc.
iOS 6 jailbrak is tethered for iPhone 4, iPhone 3GS and iPod Touch 4G, untethered only for old iPhone 3GS with old bootrom. Tethered jailbreak means that each time you restart your device you will need to connect it to a computer and run redsn0w.
iPhone 4S, iPhone 5, iPad 2 and iPad 3 are not supported.