redsn0w 0.9.11 beta 1 allows you to downgrade to iOS 5.x on iPhone 4S, iPad 2 and iPad 3!

  I told you a few days ago that a new version of redsn0w will allow us to downgrade to any version of iOS 5.x on iPhone 4S, iPad 2 and iPad 3, and today those from Dev Team have released this new version of the program. Basically, the Dev Team discovered a new hack with the help of which they allow the owners of devices with A5/A5x chips to downgrade to iOS 5.x without a bootrom exploit. Those with iDevices released before iPad 2 could do this anyway, but starting with iPad 2 the process became impossible on iOS 5.

  This downgrade system DOES BASEBAND UPDATE on iPhone 4S, so DO NOT use it if you need decoding because you will not be able to do this. Those who unlocked with SAM are exempt from this rule. Those who need unlock via Gevey or ultrasn0w MUST NOT USE this version of redsn0w. For the whole process to work YOU NEED SHSH saved in Cydia or computer and you CANNOT restore to another version of iOS than the one for which you have SHSH.

  At the end, the Dev Team tells us that the method can be blocked by Apple at any time through a software update, so use it while you still can. It should be mentioned that the Dev Team has not properly tested this process for iPad 3 GSM, so you may encounter problems during the restore process.

UPDATE: Downgrade tutorial with this version of redsn0w find here.

• You cannot downgrade without the personalized SHSH blobs for your device at that lower firmware. You need to have fetched those blobs while the signing window was open, using either Cydia's built-in TSS@Home feature, or with TinyUmbrella. The new Restore screen of redsn0w lets you choose either the remote blobs or local ones (for the earlier firmware). If you don't know where TinyUmbrella put your blobs, TinyUmbrella has a button that will show you (copy them out of that folder and feed them to redsn0w).
• The A5 downgrade method actually updates to the latest firmware before downgrading to the earlier one.  This process updates your baseband to whatever is newest.  DO NOT USE THIS METHOD IF YOU RELY ON UNOFFICIAL UNLOCKS of your iPhone4S. Those who used the temporary SAM technique to unlock their iPhones to specific SIMs should not be affected by this baseband update.
• This method can be fixed by Apple with a firmware update. It's a (pleasant) mystery why they haven't fixed it yet, because reverse-engineering of the restore ramdisk indicates they do know about it. It's possibly too niche to bother fixing right now.
• The least-tested devices with this method are the iPad2,3 and iPad3,2 (because we don't have those models). If you do and you feel like experimenting, please let us know how it turns out in the comment section below!
• This update involves a bunch of new redsn0w code. We recommend sticking to the previous version 0.9.10b8b unless you're specifically using this new feature, until all the bugs are worked out! (Note: If redsn0w gets stuck at the “Waiting for device” stage for more than 30 seconds, you've hit a pesky GUI bug…that will be fixed in an upcoming version!)