Apposite reading right now: "The Execution Channel" by Ken Macleod. Yes, it's a work of science fiction -- by someone with a background in fringe political groups who were being actively infiltrated/used for disinformation during the cold war, and who's been thinking about just how far things could go wrt. the internet.

http://www.amazon.com/The-Execution-Channel-ebook/dp/B00CBFX...