Ok. I’m behind the times on this one. Last week I was at the MSP airport, and while waiting in line for customs, I saw some impressive technology.  I was in the last stretch of those slow-moving Tensabarrier lines, and I was up next to show my papers to the T.S.A. officer. But the traveler ahead of me had no ticket. He just swiped his mobile phone over a small box next to the T.S.A., showed his license, and went on to screening.

The box had a glass face sensor like a grocery check out, and it flashed red when the phone passed over it. I didn’t catch on. It was another security measure I figured. So I dug out my own phone, and asked the T.S.A. if I needed it scanned. I didn’t. He told me that the other guy’s phone was actually his boarding pass.

The New York Times ran a piece on mobile device check in. Apparently, what I saw isn’t new. Half a dozen U.S. airlines including American, Continental, Delta, Northwest, Southwest, and Alaska have adopted the technology. But only Continental allows complete paper free passage from customs to the plane. All other airlines still require paper verification before boarding.

They look cool, and they’re smarter. According to the Times, the electronic passes use a two-dimensional encrypted bar code instead of the one-dimensional bar code printed on paper. The electronic code is tougher to crack, which is why it flies with the T.S.A.

Unfortunately, if you’re like me and use a mobile device without Internet access, you’ll need to upgrade. Palmtop computers or smartphones, like the iPhone, Blackberry, and Razr, will do the trick.