"Shimizu has worked with the Nakagawa Laboratory on a system for museums that uses visible light to convey information about exhibits to PDAs held by visitors. Viewers simply place their PDA in the path of the light coming from a nearby lamp in order to read and listen to information about the exhibit. The lamp, which can be an LED light source or a fluorescent bulb, is programmed to blink in a way that transmits a stream of data bits to the PDA. The PDA reads this stream to identify the exhibit and then plays back prerecorded information. The lamp blinks so quickly that to viewers it seems like a steady light. Also, see Talking Lights."
-- We Make Money Not Art
Also,
"Passengers at Japan's Kansai Airport will point the phones at the appropriate blinkenlights around the lounge to get information on departure times and shops and facilities, and to download music and video." (Engadget, June 29, '05)
