Civik - don't you understand that he can't upgrade to 3.0? APPLE stopped signing the files - so when he goes to restore through iTunes to his downloaded 3.0 ipsw, it will not fully install. Throughout the upgrade process, iTunes sends a ping out to Apple's servers asking them if they'll sign the files, i.e. 'authenticating' them.
Apple has stoppe signing EVERY FIRMWARE other than their current 3.1.2. So while he's restoring, iTunes will sen outthise pings, Apple will NOT sign it, the installation will fail, and he'll have a phone stuck in emergency mode.
Then, to get it working, he would have to officially upgrade to 3.1.2 through iTunes, and break his ability to unlock, maybe forever.
I'm not making this **** up man. Do some research.