This is old news -- the GAO report I'm about to mention came out two months ago and in some circles has already been discussed. But I had missed it until I saw a recent mention by Robert Poole, of Reason, on his Airport Policy Newsletter. (Here's a link to past issues; the one I'm about to quote from should be posted soon.) The GAO study really deserves more general-press and general-public discussion than it has received so far, because it illustrates an apparent new pointless extreme in security-theater thinking.
The GAO report is number 10-763, and its ungainly official title is, "Aviation Security: Efforts to Validate TSA's Passenger Screening Behavior Detection Program Underway, but Opportunities Exist to Strengthen Validation and Address Operational Challenges." Summary page is here; full 89-page PDF of report is here; PDF of summary and highlights is here. The object of the study, requested by Rep. John Mica, a Republican of Florida, was the TSA's "BDO" program and its "SPOT" process. BDOs are Behavior Detection Officers, the uniformed TSA officials who are supposed to keep a quiet eye on passengers in airports to see who is behaving suspiciously. SPOT means Screening Passengers based on Observation Techniques. For (skeptical) background on the whole idea, see here and here. From the GAO report, here's the basic idea of the "SPOT" process -- click for larger: