I just wanted to add that I bought a 32GB 3GS on Sunday. It came with 3.1.3 on it and I immediately jailbroke it and in Cydia, had it save the blobs. Today it says that it has them saved for 4.0. How was it able to get them for 4.0 when Apple stopped signing 4.0 last week? The phone is still on 3.1.3.
Maybe the original owner backed up the 4.0 SHSH just in case through tiny umbrella?