] The technology works by detecting radiation leakage
] that is emitted when antennae are tuned to a given
] radio station.
]
] The sensors, positioned on the billboard poles, could
] capture the signals of 60 to 85 percent of the passing
] cars. The company is promising advertisers the
] technology will capture the listening patterns of
] 60 percent of the cars.

An article from today's New York Times is available on the company's web site. When it goes away, you can find it at

http://www.nytimes.com/2002/12/27/business/media/27ADCO.html?pagewanted=print&position=top

New Billboards Sample Radios as Cars Go By, Then Adjust