Notcom has released TinyUmbrella 5.10.15 for Windows and Mac which includes minor bug fixes, especially for original iPad 1 users, as they experience errors while trying to save SHSH blobs using any previous version of TinyUmbrella tool.
Download TinyUmbrella 5.10.15 for Mac
Download TinyUmbrella 5.10.15 for Windows
See also:
Download iOS 5.1.1 for iPhone, iPod Touch and iPad
How to Save SHSH Blobs with TinyUmbrella
How to Save SHSH Blobs with iFaith