Ever since the week that 4.0 came out, I had downloaded and installed 4.0 beta on 3gs. The only thing that went wrong was that the device wouldn't activate despite its device id (40char) already been registered. I tried even deleting/resubmitting the id through the dev portal, but no luck. I even contacted Apple, they said that it's "beta software" and that they can't do anything. Only gave me address to differing department of Apple support that recently just told me that there is nothing that I can do. So I thought, why not just decrypt the .ipsw and change some permissions.
Despite this being my last resort, I couldn't seem to find the rootfs.dmg that everyone says is within the extracted file.
Just any tips, suggestions, tutorials, anything... that anyone can do to help.