Download The Firmware Umbrella: http://thefirmwareumbrella.blogspot.com/
In this video I show you how to back up your SHSH blobs on your iPhone, iPod touch and iPad using Firmware Umbrella. Using this tool allows you to locally save your SHSH blobs for iOS 4.1 for the iPod touch and iPhone and iOS 3.2.2 for the iPad. I also show you how to use the SHSH blobs to restore to whatever firmware you need through iTunes to always ensure you can get back to an earlier version of iOS.