This is why I call the TSA "The Transportation Stupidity Agency" - a DefCon attendee travelled without ID to see how the procedure worked, and spotted some problems:

For one, thing Davidoff didn't need to know much in order to establish her identity: She had to provide her name along with both a street and a state where she'd previously resided.

She said that this kind of basic information is pretty easy to dig up.

Another problem was that the TSA's first screener marked up her home-printed boarding pass with a red Sharpie pen. This was the sign for the workers at the metal detector to give here a more thorough screening.

She believes that If she had simply printed two copies of her boarding pass, she could have handed in an unmarked copy and skipped this secondary screening, which included a pad-down and a test for explosives.

So basicaly, claiming that you've forgotten your ID, using a copy machine, and doing some basic research will get you through with minimal checks. I love dog and pony shows...