My rules (which usually follow very closely to Andrew's, mind you) are that you can't use the board to discuss illegal activities. You can usually get away with a mention that it can be used for illegal purposes, as long as you specifically state that you're information pertains only to the legal side of things. Hope that clears some rules up for you guys.
Basically, you can say "why", but not "how" something is done. His question, for example, was fine. As far as I can tell, there's nothing illegal about changing the name outputted by the caller ID. In fact, it's a common feature on most cell phones. Continue, my friends.