Research groups are claiming they cracked Keeloq, the security system used in key fobs by Toyota as well as GM, VW, Fiat, Chrysler, Daewoo, Honda, Jaguar, and Volvo. Seems some things were leaked to a Russian hacking website allowing the researcher to open the door and start the car. It takes an hour, so if you see a college kid with a lap top hanging around your Prius... for a really long time, he might be trying to steal it.
Last I looked into it, Keeloq was based on a rolling code. But it looks like they screwed up the key generation; it's fairly easy to find 36 of the 64 bits. The remaining
1 EYE R SMRT ENGINERD! DAH-HUR!!1!