Security Problems for RFID?

Graduate students at Johns Hopkins University have uncovered a method of cracking the encryption surrounding RFID, so reports
Non-technical results are posted at
RFID systems are used in automotive keys so that a signal from the key is necessary to start the car. It is used in Mobil SpeedPass and it is used in Wal-Mart inventory.
The writers point out that the 40 bit encryption is rather trivial to hack. What is needed is AES encryption. The problem is with the long rollout cycles for automobiles, this is not a change that will occur immediately.
Of course with speedpass I still think the primary issue is when someone steals your keys they now have access to your credit card (without signature necessary) at every Mobil/Exxon station.