iPhone Dev Team new Redsn0w version has released for you. This version is 0.9.11b2, this new version has A5 firmware downgrade feature. You can downgrade new devices like iPad2, iPad3, iPhone 4S iOS 5.1.1 or iOS 5.1 to iOS 5.0.1 .
Download Redsnow 0.9.11b2
Click Previous version Redsnow 0.9.10b8b extras button and click new version extras button then you can see additional features with new versions.
Redsn0w team has fixed most of the bugs. But if you faced with any problem they asked to comments to them using dev team blog. They have clearly mentioned missed out including support for two flavours 9A406 of 5.0.1 of iPhone 4S and it will add with next update. 0.9.11b2 version is adds support for 9A406 flavor of iOS 5.0.1. You can visit dev team blog for more information for this release.