What data is on your hotel card key?

ComputerWorld has a good article on what data they did and did not find on hotel card keys from various U.S. chains. They generically claim that some European and older U.S. card key systems put personal information on hotel card keys, which could leave guests vulnerable to ID theft or other privacy violations. The article's author, Robert L. Mitchell, concludes that current card keys used at major U.S. hotel and motel chains are OK, although in some cases they found data which they were unable to decode. Via Emergent Chaos.