This highly informative (and very worrying) talk was given by Malte Spitz, a German politician of the Green Party, at a recent TED conference. It's well worth your time to watch it.
You can read more about the problem, including viewing an animation of how much his phone company knew about Mr. Spitz, by clicking here.
I knew that all sorts of people, companies and agencies were watching almost everyone . . . but I never knew their information about us was so detailed and intrusive. The question is, how can it be reversed - if at all?