The well known iPhone hacker MuscleNerd has just posted on his Twitter account that an upcoming release of redsn0w will make TinyUmbrella and Cydia blob saves useful for iOS 5.0 and 5.0.1.
Well, the Dev Team member, MuscleNerd is now working on new update of Redsn0w introducing new features for Mac and Windows. The new update will make you able to downgrade the firmware even on the most recent version of iOS using Redsnow.
As obviously, currently the only tool that allows you to do so but not for much longer is iFaith of iH8sn0w.