are only a token effort by the Entertainment Industry... They aren't intended to stop the flow of data, they are intended to show that "They Tried"... (in legalese, "made a good faith effort")...
The reason that is necessary is to protect their image (public and legal) when they file suit against the "John Does" corresponding to all the IP addresses they have logged.

I couldn't help but notice the poor fellow who believes that "IP addresses are useless"... possibly because many ISPs give you a new one every time you sign on. However, they are required to keep logs of to whom each Address was assigned...

Please see the "Future of Gnutella" section of my (horribly debris-ridden, still under construction) site
http://members.aol.com/vbhydrophonic/index.html