TinyUmbrella allows users to save their iOS device's SHSH blobs (Signature HaSH blobs) in order to downgrade iOS versions at a later date. Therefore, those who are waiting for the iOS 6 jailbreak in the future must download the new version of TinyUmbrella and save their SHSH blobs.
"I've updated TU for apple tv 5.0.2 (sorry for the wait!) as well as all of the iOS 6 betas. I've had to change the way the OSX app is packaged," NotCom said in his blog post.
"So now it is a simple zip but you will have to give your admin password at the first launch."
An SHSH blob is a signature file, used against the Apple server to downgrade a device to an earlier version of iOS. After Apple releases the iOS 6 update, if any user upgrades his device to the latest built, these saved SHSH blobs will help downgrade the firmware. Without these SHSH blobs, users won't be able to downgrade to old ipsw to re-jailbreak the iOS device (if exists), according to Cydia Blog.
Here are the steps to follow to save iOS 6 SHSH blobs:
Step 1: Download TinyUmbrella v6.00.00b.
Step 2: Connect the device to a PC or Mac via USB.
Step 3: Double click on the ".dmg" file to mount it and drag the Umbrella app from the mounted dmg into your Applications folder. After that, double click the Umbrella app to launch it.
Step 4: Enter administrative username and password. TinyUmbrella will then detect the type of device and its firmware.
Step 5: Click the "Advanced" tab and uncheck "Set Hosts to Cydia on Exit" and "Request SHSH from Cydia".
Step 6: Now hit the "Save SHSH" button.
[Source: Cydia Blog]
Once you finish the process successfully, you should notice a new entry in the Saved SHSHs for iPhone list. If the saved file contains 60-65k bytes of data, then the file should be fine.