Pedestrian Cell Phone Collision Avoidance

I have recently had the unusual experience of watching people on foot in parking lots or side roads walking STRAIGHT TOWARD my (moving) vehicle whilst talking on their cell phones. Apparently the mental contortions involved in fumbling for their car keys, operating their PDA, talking on their mobile, and trying to look for their own vehicle cause them to either a) subconsciously seek to end it all or b)give in to some primitive tendency to flock to large metal objects or c) simply not watch where they're going.

Proximity/metal detection is nothing new. The cell phone is already spewing radiation within a cm of your cranium, why not add a microwave emitter?

The cell phone could emit a rude squawking noise in the earpiece when a large metal object gets too near.

Might be a little difficult to use a phone equipped with this feature while you were *in* a large metal object, such as a car, but hey, that's not *all* bad... :-)