Thank you for the explanation. I installed TinyUmbrella, connected my iPad 2 and saved the 4.3 blob. I have a question though, is the blob that I saved unique to my device and the reason why I wouldn't be able to just use someone else's saved blob?
I also don't understand why I'm allowed to save my blob right now, but you stated that I may only have minutes to save my blob. Why wouldn't I be allowed to save it later on? I'm confused, because I just connected my Jailbroken iPhone 4 running iOS 4.2.1 to Tiny Umbrella, and it saved SHSH blobs 4.0.1, 4.0.2, 4.1, 4.2b3, and 4.3
No, you cannot use another person's blob. It is unique to your device, not just to the version of iOS.
You can save your blob because apple is still signing 4.3. You won't be able to do this shortly.
SHSH's from your Jailbroken iPhone 4 for each of those probably showed up because Cydia was saving them for you. You cannot get blobs for any of those (besides 4.3) anymore because apple is not signing them anymore. But if Cydia was backing them up for you, you will have them.