When thieves in Malaysia made off with a car recently, they didn't stop with the machine itself; its owner also lost the tip of his index finger, which the car's fingerprint recognition system needed in order to engage the ignition. The incident has sparked calls for live-ness detection in biometric security systems--for example, fingerprint recognition systems that check for perspiration to ensure that the finger in question is still attached to a (living) body.
Biometrics is a very fine security technology in principle, but it does pose some subtle hazards--not least of which is the potential loss of key body parts. (Dan "Davinci Code" Brown's Angels and Demons, for example, has a very...intense...scene involving a retina scanner.) And of course many people have physical deficits (lost limbs, worn finger pads) that render them "invisible" to some biometric security systems. Face recognition (pace Hannibal Lecter) seems like one good solution to the problem, although the technology isn't (yet) as robust as one might wish.
Okay, if I'm so smart, what's my solution? You may not like it: X-ray skeleton recognition. That's right: I propose to turn your body into one giant biometric key and irradiate it each time you need to establish your identity. I even have a motto for the system's manufacturer: "It can be kidnapped, but it's really hard to remove." Ah, once again, I detect the sickly sweet smell of an indefensible patent application...