The National Research Council recently published a 376 page report entitled "Protecting Individual Privacy in the Struggle Against Terrorists: A Framework for Program Assessment" . The report, written by the Committee on Technical and Privacy Dimensions of Information for Terrorism Prevention and Other National Goals of the National Research Council looks at the science behind data-mining and behavior-detection techniques used by government agencies to spot terrorists. They find these techniques to be questionable, and warn that they could violate privacy of law-abiding Americans. They conclude that all U.S. agencies with counterterrorism programs that collect or "mine" personal data -- such as phone records or Web sites visited -- should be required to evaluate the programs' effectiveness, lawfulness, and impacts on privacy.
BTW, you can read the report for free online and if you go to the Table of Contents there's a nifty little feature that lets you "skim" the various sections of the report.