Of course, P2P spyblockers are just like antivirus programs, only as good as the last update, and useless against anything that comes out afterwards.
They work by barring certain lists of IP addresses, although those lists may be incomplete or grossly inaccurate.
They have other uses, in barring other lists of known sources of objectionable content.
One day, you will get, at best, a cease and desist via your ISP.
Seen others mention it on my ISP forums, and it sure gives me the jitters about getting involved, even with the aid of "protection".