Room’s Ambience Fingerprinted By Phone

DURHAM, N.C. -- Your smart phone may soon be able to know not only that you're at the mall, but whether you're in the jewelry store or the shoe store.

Duke University computer engineers have made use of standard cell phone features – accelerometers, cameras and microphones – to turn the unique properties of a particular space into a distinct fingerprint. While standard global positioning systems (GPS) are only accurate to 10 meters (32 feet) and do not work indoors, the new application is designed to work indoors and can be as precise as telling if a user is on one side of an interior wall or another.

http://news.duke.edu/2009/09/surrsense.html