I have the 3GS and I just jailbroke it for the first time using JailbreakMe.
When I first bought it, it was my first iPhone/touch device and I upgraded the OS to 4.0.1 without realizing that it would hinder jailbreaking in the future.
I've now got it jailbroken but I did not save my SHSH Blobs as I did not know about them. I hate the 4.0.1 OS because it is so slow and choppy and I would like to downgrade to iOS 3.
Is there a way to downgrade AFTER I've jailbroken WITHOUT the SHSH Blobs? I'm not sure if the fact that I'm jailbroken makes it any easier?