An article from CNet discusses a recent drop in Netratings traffic ratings for file sharing services (down about 15% since the end of June).

It's an interesting (and provocative) theory, but I'm not sure I agree with it. With the beginning of summer, you see fewer college students, and there is good reason to believe they contribute disproportionately (when they are in their dorms) to the amount of file sharing traffic. Anecdotal, yes, but the Netratings stuff isn't exact either, it is using a sample of 50,000 users, not a backbone monitoring system or some such.