I was reading through the September issue of Car and Driver and came across a funny story:
Nathan Rau, a 31-year old lawyer from Minneapolis, MN, contacted the New York Times to let them know that the key to his Audi was confiscated by airport security at Dallas/Ft.Worth International Airport. While Rau was passing through a security checkpoint, guards noticed the switch-blade-like key (Press a button and the key flips out) in the X-Ray machine. Rau was told he wouldn't be allowed to fly with the key because, "Well, sir, that's a switchblade style, and that's a prohibited item. We're gonna have to confiscate that." Fortunately, Rau keeps a key hidden on his car and was able to drive home from the airport. Unfortunately, replacing the confiscated key can cost about $300.

That's so dumb... You can't do any damage at all with an Audi key..