Here is Powerline's take, "NSA Accused of Protecting US from Terrorists":
Liberals are jumping up and down about USA Today's publication of another leak relating to the National Security Agency. It's considered a news flash that the NSA is collecting data on phone calls, with the cooperation of almost all of the major telecom companies, to look for suspicious patterns. This is a "data mining" project that does not involve listening in on conversations, but merely identifying phone numbers involved in possible terrorist communications.....And John Hinderaker goes on to say that a capability like this would most likely have prevented the London subway bombing, another story carried in the Tribune today, as police were monitoring suspects but were undermanned and unable to connect the dots.
Two, it's obvious that what the NSA does with this vast amount of data is to run it through computers, looking for suspicious patterns, especially involving known or suspected terrorist phone numbers. I did a quick calculation: assuming that there are 200 million adult Americans, each of whom places or receives ten phone calls a day (a conservative estimate, I think), it would require a small army of 35,000 full-time NSA employees to pay a total of one second of attention to each call. In other words, lighten up: the NSA obviously isn't tracking your phone calls with your friends and relatives.
UPDATE: Most Americans support NSA surveillance. Washington Post-ABC News poll here.