This is the end product of the search for Bin Laden. Bin Laden was smart and did not communicate electronically, but he had associates. They began working on network software that keeps track of all known connections between people, a six degrees of Bin Laden. The same people later worked on social sites like Facebook.
The CIA does not need to spy on Facebook per se, it hacks into the fiber optic cables and reads all the raw packets, and assembles them into emails and phone calls.
Plain text, 'Man-in-the-Middle' without modification interceptions.