You have to believe they do monitor all public postings, though that is a job in itself. 2 thoughts about that: 1) they could probably justify secret rooms and

You have to believe they do monitor all public postings, though that is a job in itself. 2 thoughts about that: 1) they could probably justify secret rooms and data gathering on the volume of public traffic alone. In other words if they are hitting the public APIs millions of times a day, Twitter, FB, et al. Would rather give them privileged access. Then whoops, might as well read all the private stuff as well. 2) just imagine the power of analyzing topics, trends, and personalities on all public forums across the Internet, US and international! Google indexes it, but what if the NSA were able to make sense of it somehow. From usernames and posting profiles alone (and maybe language analysis) they might be able to bullied a DB of online personas. Of course, if they could read everybody's email or get IP addresses from servers and ISPs, then they could easily correlate with actual persons.