Continental Airline is the first US airline to announce a pilot program for using the cell phone or a PDA as boarding passes. Air Canada, Spanair and serveral other airlines around the world are already offering it for some time. Continental is piloting it at the Houston Airport. In US the TSA will scan the 2-D bar code directly from your mobile device. This is the same barcode that you see when you print your boarding pass at home and many of the airlines today scan it at the gate. The passengers will be required to show a valid photo ID, which I am not sure why, ID is not required if I print the pass at home.  Don't worry if you forget your phone home or if the battery dies, you can alway re-print a copy from the Kiosk at the airport. I certianly have printed my boarding pass at home and left it there a few times :-).

At this point, there are some limitation, for example, a famliy traveling together will not be able to use it, unless everyone in the family has their own cell phone. Based on the success of these pilots, Continental Airlines will determine its plans for extention and hopfully other airlines will follow.

I am looking forward to seeing this offered at the Oakland airport, where I fly out of more often that I would like to. Then I can check in while driving to the airport and talking on the phone. But atleast, I don't forget my phone home, unlike my printed boarding pass.

PS. The 2-D bar code stores the passenger's name and flight information in an encrypted format, the authenticity of the bar code is confirmed at the time of scanning.