An iPHONE 3GS application from Acrossair offers a new way to navigate the urban jungle of several major cities. The system uses the iPhone display as a viewfinder for the phone's built-in camera. Pointing toward the ground will call up arrows indicating the locations of all the city's subway or light-rail lines. Holding the iPhone horizontally will overlay labels on the scene identifying the locations of the nearest stations, along with the distance to each one and the lines it serves. Acrossair has released versions for New York, Chicago, San Francisco, Washington, DC, Barcelona, London, Madrid, Paris, and Tokyo.

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