Skilled iOS developer Notcom, has just released TinyUmbrella 5.1b1 for both Mac OS X and Windows. TinyUmbrella 5.1b1 delivers support to save iOS 5.1 beta SHSH blobs (ECID SHSH). Apple had seeded iOS 5.1 Beta to developers of iOS Developer program couple of days back.
These backed up SHSH blobs will help you to downgrade your iDevice firmware to previous firmware as Apple usually stops signing them after a new iOS software update is released.
Unfortunately, at present there is no way to downgrade the iOS firmware on the iPhone 4S because Apple now signs the firmware during the restore process. But it is always a good practice to backup the SHSH blobs, as one never knows just what the future holds.
Notcom reiterates on his blog post – even though there is no way for restoring iOS 5x on an iPhone 4S, he has released the update so users can at a minimum still save 5.1 beta SHSH blobs. He is currently trying out for 4.x baseband based restores to avoid 10xx errors.
So what are you waiting for? Hit up TinyUmbrella and download the latest version TinyUmbrella 5.1b1 for both Windows and Mac.