The RFID system is on my mom's M35. Very cool. Key never has to leave your pocket. (And for those smart asses out there, there IS a key inside the fob to lock the glove box.
)
Anyway, you walk up to which ever door or truck and hit a button that unlocks that door. Hit a door button twice and it unlocks all the doors. It's really nice when I drive her car and just get in, [move the seat WAY back] and start the car.
Unfortunately, this isn't hacker proof. There's a German team that was able to successfully prove that they could steal any car using this system with a laptop and 5 minutes. The problem is that these RFID tags that are built into the fob are only 40 and 60 bit encryption. So it doesn't take very long to decode them. However, it does take a serious PRO to do it. I was thinking about trying it myself, but I don't want to spend money on an RFID transceiver.
Aside from that... Get lo jack and enjoy the awesomeness that it key-free driving.