Next time you're driving in parts of CA and you turn the dial on your car radio, no matter how high or low you set the volume control, you won't be the only one listening.
Interstate 280, Interstate 880, and Highway 101 will soon sport electronic billboards that collect stray radio waves from car antennas, calibrate the most selected radio station, and use the radio station's listener-profile data to determine relevant advertising. Eminem fans, for instance, might be told where to buy the coolest pair of overalls.
Future billboards will communicate with one another, and thereby coordinate advertising across vast stretches of highway.
Coverage is here.