The Washington Times confirms Annie Jacobsen's account of the strange goings-on aboard American flight 327 in this article titled "Scouting jetliners for new attacks":

Flight crews and air marshals say Middle Eastern men are staking out airports, probing security measures and conducting test runs aboard airplanes for a terrorist attack.

At least two midflight incidents have involved numerous men of Middle Eastern descent behaving in what one pilot called "stereotypical" behavior of an organized attempt to attack a plane.

"No doubt these are dry runs for a terrorist attack," an air marshal said. Pilots and air marshals who asked to remain anonymous told The Washington Times that surveillance by terrorists is rampant, using different probing methods. "It's happening, and it's a sad state of affairs," a pilot said.

This incident struck me as particularly shocking:

A second pilot said that, on one of his recent flights, an air marshal forced his way into the lavatory at the front of his plane after a man of Middle Eastern descent locked himself in for a long period.

The marshal found the mirror had been removed and the man was attempting to break through the wall. The cockpit was on the other side. The second pilot said terrorists are "absolutely" testing security.

I've been skeptical about these stories, mainly because I fly so much that if a lot of this activity were going on, I think I would see it. Of course, there are thousands of flights and I ride only a relative handful of them. Reading the Times' account, it's hard to remain skeptical.