Updated TinyUmbrella version 5.10.00 is out there for Windows and Mac that includes support to save iOS 5.1 b1 SHSH blobs over iPhone, iPad and iPod touch.
How to Save SHSH Blobs with TinyUmbrella
Those who are not familiar with TinyUmbrella, this tool works to save SHSH blob for iDevices including iPhone, iPod Touch, iPad and Apple TV from Apple Server and Cydia which are required to downgrade iDevice firmware to an older version.
Download TinyUmbrella 5.10.00 for Windows
Download TinyUmbrella 5.10.00 for Mac