As mentioned previously, this exploit in Apples apticket system can prove to be very helpful. There is no jailbreak, tethered or untethered, available for A5 based devices on iOS 5.1. A new jailbreak has been teased by iPhone Dev Team and Stefan Esser, but theyre far from release. Those who have mistakenly upgraded their iPad 2 or iPhone 4S to iOS 5.1 can not jailbreak it now because none is available for it. iOS 5.0.1 is the only firmware that can be jailbroken untethered on iPhone 4S and iPad 2 right now. Being able to downgrade iOS 5.1 to iOS 5.0.1 will prove to be very beneficial for those who have mistakenly upgraded A5 devices.
Do keep in mind that saved iOS 5.0.1 SHSH blobs will probably be an imperative component in order to downgrade iOS 5.1 to iOS 5.0.1. Youre set if you saved iOS 5.0.1 SHSH blobs when it was possible, because now it isnt. iH8sn0w hasnt revealed any more details regarding this exploit and I dont expect he will until its ready for release. iOS 5.0.1 can be jailbroken untethered on iPhone 4S and iPad 2 right now using Absinthe for both Windows and Mac
-cydiahelp
http://cydiahelp.com/downgrade-iphone-4s-ipad-2-5.1-to-5.0.1-now-possible/