I love the iphone, I did the unlock/jailbreak and teathered the shit out of it for the last 6 months, then one day same thing, it geeked out and wouldnt go past the apple screen. To fix it you have to plug it into teh computer with itunes on and hold both buttons, when it shuts off and reboots, keep holding the buttons and it will go into some special mode that only nerds really understand but it allows itunes to connect to it even if its fucked up. I had to reboot it and update the software and in turn lost the unlock/jailbreak and with that teh teathering ability. The supernerds said they have the next unlock ready but will not release it until the iphone 4 is out so apple/att&t dont cover it up before the new iphone is out.
I love the iphone and will be pre-ordering a iphone 4 today. The thing is like my car, I've had it apart sooo many times fixing stupid shit but its easy to work on once you do it once or twice.