Tim O'Reilly, of O'Reilly and Associates (publishers of fine IT books (and how deeply can I parenthesize and tangent off before even I lose the thread?)), has a bit to say about file-swapping. Of course he isn't quite the authority on MP3 warez as he is on books, but he's still in the mass-media content business. Consequently, his opining probably carries more weight than does mine (which, if you're curious, is "MP3 sharing hasn't seemed to hurt CD sales yet ... what makes you think it's going to in the future?").