MuscleNerd has revealed that there is an unreleased technique which can downgrade A5 devices on iOS 5.1 and iOS 5.1.1 to iOS 5.0.1 for an untethered jailbreak, according to the latest information revealed from iOS 5.1.1 firmware.

5.1.1 shows Apple knows about an unreleased technique to downgrade A5 devices to 5.0.1 with saved blobs (but left it alone..hmm)

It's unclear why Apple would leave this technique alone. Maybe it wasn't worth fixing because it hadn't been made available.

Notably, this technique is different from the one found by iH8Sn0w in that it does not use copyrighted Apple code.

Unfortunately, we don't know when or if this technique will become public. Hope it could be released before iOS 6...