Sylvia Else

Once you enter the realms filtering peer to peer traffic, you're embarking on an arms race with those who want to hide their activity from you. The mere fact that technology might exist today that can filter peer to peer traffic doesn't mean that it will still work tomorrow. In any case, on the face of it, filtering attempts would be roundly defeated in the first battle as traffic becomes subject to public key based encryption. Of course, those wishing to sell the technology won't be admitting its limitations. They'll just sell you (by which I mean the ISPs' paying customers) a lemon.