My girlfriend's iPhone was stolen in a subway station. She immediately rushed home to track it in Find My Iphone. However, the phone had been switched off immediately of course.<p>If there were an iphone cover that cannot be taken off easily and blocks the power button, you could trace your phone for much longer. And who needs the power button anyway? You could of course take it off with a special screwdriver or a small code lock or something.
I use the power button to lock the phone (turn off the backlight), to mute incoming calls when the phone is in my pocket, and to take screenshots. It would suck for me (and a vast majority, I think, of people who do the same) to have to take off the case with a "special" screwdriver.<p>A better option would be to prompt the user to enter their passcode before turning the phone off, if at all the user has set a passcode.