Just saw this story today.. check out The Car Whisperer. Basically, with a linux laptop and a directional bluetooth antenna, you can connect to cars that have bluetooth capability. You can do this since most bluetooth-enabled cars have standard easy-to-guess keys, I suppose.

The result is you can pipe audio into their car, or listen to what they're saying, using the bluetooth cell phone equipment in the car.

Since my C is very rusty, and I don't have a Linux laptop handy, and I don't have a bluetooth-enabled car to play with.. I won't get very far. Just wondering what you people think about it.