A team of students from John Hopkins university was able to crack the key-code system used by Ford, Toyota and Nissan in their car keys.
With some documentation found on the web, they were able to reverse engineer the system (made by Texas Instruments) and break the key system (it's a 30 bit key; for comparison, most browsers today use a 128 bit key). With a radio scanner, they're able to scan a key's transmission, then decrypt the code and feed it back to the car.
I don't think it shows that the system was insecure; rather, computers are now so much faster that a 30 bit key, which was a big number 10 years ago, is tiny by today's standard.
And anyways, no car is really secure from a flatbed truck.
There's an article on this at the New York Times(reg. required) and some comments up on Slashdot.
