Redsn0w has been updated to version 0.9.11b and now allows you to downgrade the iPhone 4S, 2 and New iPad iPhone third generation.
At 4 and previous iPhone they could do because of Limera1n, a bootrom exploit, but do not have that type of exploit in iPhone 4S or later, but now you can download your SHSH and IOS IOS 5.1 and 5.1.1 to 5.0. 1, the problem is that to do this process first upgrade to the latest version and then down to 5.0.1, so it will raise the baseband, if you need to release you can not use it, if you rely on the release will have no problem with SAM, only need to have saved the Lockdown folder.
This new way to downgrade Apple can be closed easily with a software update.
You can download Redsn0w 0.9.11b1 here: