Part of the explanation for the NSA’s acquisition of phone records from Verizon and other carriers has been the assurance that no G-men were listening in on phone calls.  All they got their hands on was metadata – not the content of the calls.

Wired has a great take on why that excuse is bunk:

Metadata is our context. And that can reveal far more about us — both individually and as groups — than the words we speak.

Context yields insights into who we are and the implicit, hidden relationships between us. A complete set of all the calling records for an entire country is therefore a record not just of how the phone is used, but, coupled with powerful software, of our importance to each other, our interests, values, and the various roles we play.

Still not convinced?  Listen, my children, and you shall hear an even better analysis: Had the Redcoats around Boston used metadata analysis in April of 1775, then Paul Revere would have been toast.