TinyUmbrella was immediately revised and updated to fix some important fixes for Apple TV 2/3 after its update on 18-Mar-2012. TinyUmbrella is used to save SHSH blobs to Cydia which you can use to degrade your iOS 5.1 in case you want to revert back to iOS 5.0.1 because untethered 5.1 jailbreak is still not available. You can download the latest version of TinyUmbrella 5.10.09 from the links below.
Many people face the error 3194 which is an issue with attempting to restore and having iTunes not verify the SHSH blob. Some times it may be caused by TinyUmbrella being open and can be resolved by closing TinyUmbrella although it does not work in all cases.
Alternatively you can use iFaith for saving 5.1 SHSH blobs which is also a good software,which was also recently updated to save SHSH blobs for ios 5.1.