Security is a fascinating topic, and a long one if you really wanted to go into it.

Lets go for the most common, bond/mission impossible inspired security: fingerprint readers. Is it easier to take a copy of a fingerprint, or just to chop a finger off and use that? Sometimes the latter will be easier, and it happens (http://www.schneier.com/blog/archives/2005/04/security_risks_2.html). This kind of story isn't uncommon.

What is more interesting is gait-recognition. How is someone going to steal your gait? If a camera watching you walk down the corridor could verify you are you, not requiring any knowledge inside your head, or bits off your body to let you in the door then isn't that a great concept? Ah, but you'd have to make sure that putting a video playback of your walk in front of the camera wouldn't fool it, like the photocopied fingerprints.

So now lets revisit the laptop thing. Gait recognition is presumably impractical - I'm not up for walking around the opposite side of the room in starbucks just to login (http://uk.youtube.com/watch?v=IqhlQfXUk7w). Fingerprint recognition I'll stay well clear of for as long as I can. If you work for a company that wants to make fingerprint recognition mandatory it might be worth asking them if they are going to pay all the employees danger money on a per-finger basis.

How about a simpler approach? Let them steal the laptop, and even give them the password if your life or limb is risked (http://www.truecrypt.org/docs/?s=hidden-operating-system), they don't have to know its the wrong one. You might have to make sure you can turn if off before they get to it so that it boots up when they first switch it on. Less practical with cars though, I'm not sure what you'd have as the alternative to the real OS - lock them in and spray laughing gas through the aircon?

Andy