Saurik's on "Caching Apple's Signature Server"
All iphone 3GS owner should be reading this post by Saurik, the creator of Cydia.
Please read here: http://www.saurik.com/id/12
I know many users reading this thread probably missed out the window when you could have allowed Cydia to store your ECID/SHSH.
However, not all hopes are lost. MuscleNerd from the Dev-Team recently stated the following
STAY CLEAR OF APPLE OFFICIAL FIRMWARE 3.1 UNTIL FURTHER ANNOUNCEMENT.
Originally Posted by MuscleNerd