ISPs are talking about getting into the copyright-enforcement business. It's hard to see where this will end, once it gets going. Privacy advocates are not going to like it, nor should they.
But I wonder if the effort misses the point, anyway. The end goal is for copyright holders to get paid, right? So why not just levy a "tax" (or subscription, if you will) on all broadband users at $5.99/month (or whatever the price should be). Make it mandatory unless someone agrees to have their bandwidth filtered for copyrighted content (unless bought through iTunes or other legitimate means). Then distribute that revenue between the various copyright holders in the entertainment industry.
Sound familiar? It should. This is not too dissimilar from what the music industry already does with ASCAP.
This model would have the benefit of encouraging a multitude of means of discovering, downloading, and trying new content...with the copyright holders getting paid in the process. What is there to lose?