Apparently they're too busy looking for reading tips:
The U.S. government is collecting electronic records on the travel habits of millions of Americans who fly, drive or take cruises abroad, retaining data on the persons with whom they travel or plan to stay, the personal items they carry during their journeys, and even the books that travelers have carried, according to documents obtained by a group of civil liberties advocates and statements by government officials.
The personal travel records are meant to be stored for as long as 15 years, as part of the Department of Homeland Security's effort to assess the security threat posed by all travelers entering the country. Officials say the records, which are analyzed by the department's Automated Targeting System, help border officials distinguish potential terrorists from innocent people entering the country.
The book thing is what seems to have been getting the most attention around the blogosphere, but I think the rest of the article is far more important. For one thing, having been through quite a few airports (and a couple of customs barriers) in the past year, I frankly doubt that federal agents have either the time or the resources to paw through people's luggage on any kind of a regular basis. Unless they're actually riffling through checked baggage before they allow it to be loaded, they'd have no way of knowing what books most travelers are carrying, as books are transparent to X-rays. (I know: I've carried quite a few of them through quite a few TSA checkpoints.)
Plus, air travel reached record levels this summer, rebounding after several years of decreased volume in the aftermath of the Day That Changed EverythingTM. Airlines, airports, and the TSA itself, on the other hand, either seem not to have noticed the ever-growing flood of people pouring in to avail themselves of their services, or really don't care anymore--because staffing levels have either declined or, at best, remained steady. It already takes a good 25-30 minutes, in my experience, to make it through the security lines at most airports. Taking the time to riffle through everyone's carry-on luggage to look at what sorts of "subversive" materials they might be carrying would effectively double or triple that wait time--and probably quintuple the number of complaints received about the holdups.
It's no skin off my nose if TSA want to see what I'm reading. Chances are good that they wouldn't even understand the titles of a lot of what I carry through airports, since it tends to be academic tomes--and often in foreign languages. I draw the line, however, at suggesting that what someone reads is any real indication of his or her inclination toward terrorism or the overthrow of the U.S. government.
For example, I know a member of our faculty who researches the effects of psychotropic drugs. In his hands, a "book on marijuana," such as the one referenced in the WaPo story linked to above, might mean nothing more than the routine conduct of his academic research. In the same way, I regularly buy, check out of libraries, and carry around with me, books on ethnic cleansing, genocide, fascism, Nazism, and authoritarianism: because I'm an historian, and these are some of the things I study in depth. Doesn't mean I'm planning to emulate anything that I read about.
In fact, when you get right down to it, nobody in her right mind would ever expect such a data-collection enterprise to turn up a real terrorist, unless the terrorist in question were truly stupid--and those are the ones we don't have to worry about. The ones we want the TSA and Homeland Security to catch are the smart ones, the ones that actually have a chance of carrying out their plans. But they are too smart to be caught walking through an airport security check, or crossing an international border, with anything that might potentially reveal their intentions. It would be wonderful if all terrorists were required by some obscure bylaw to carry with them at all times a copy of Terrorism for Dummies (conveniently in English, of course, the better to catch the attention of our sniveling servants who can barely manage to be coherent in one language, let alone two or three)--but that will never happen.
Meanwhile, as they attempt to keep track of People Who Might Cause Them Trouble, our government is quite likely to be missing the people they really ought to be watching. And of course, in order to piece together just who might be likely to give them trouble, the government has to collect far more data than it would like for us to know about, to keep it for far longer than they've promised they would, and to look at it and manipulate it in ways they promised they wouldn't. This should surprise no one--and outrage everyone.