Few minuts ago MuscleNerd has announced that the upcoming RedSn0w can restore and downgrade your iPhone 4S and iPad 2/3 for users with SHSH Blobs preserved.
Update is a specially for iPhone 4S, iPad 2/3 users, simply because they could finally have the ability to downgrade their devices.
Remember that iOS firmware downgrade is limited to non-A5 devices, because Dev Team still haven't a bootrom exploit for A5 and A5X devices.
Note: You'd only have the ability to downgrade your iPhone 4S, iPad 2 / iPad 3 if you have saved SHSH blobs for the right iOS firmware version that you want to be downgraded.
Upcoming RedSn0w Will Allow you to Downgrade iPhone 4S and iPad 2/3
Downgrade iPhone 4S — iPad 2 / iPad 3 Status
This downgrade method is different from the iH8Sn0w's downgrading method for iOS 5.1 to iOS 5.0.1 on iPhone 4S / iPad 2/3. Downgrading will allow to users with SHSH Blobs saved — to downgrade their A5 / A5X devices to iOS 5.0.1 to have an untethered jailbreak.