Future Room Lighting to Double as Light "Wi-Fi"... or eavesdropping device.

VLC transmits data wirelessly using visible light as its medium instead of radio waves... Harold Haas, professor of Mobile Communications at the University of Edinburgh, successfully demonstrated the VLC technology at a TED conference. He streamed a HD video to a screen using a LED light bulb as transmitter.

Haas co-founded PureVLC, a corporate spin-off of the university’s research project, to turn the technology into commercially viable devices. The company is now beta-testing its first product: the Smart Lighting Development Kit (SLDK)...
 
Because the light changes superfast it is invisible to the human eye and can still function as normal lighting.

A standard Ethernet port connects the ceiling unit to a data network. The unit encodes the data onto the current feeding the LEDs. The desktop unit receives the data, decodes it and transfers it to a laptop or desktop computer. It can also send data to the ceiling unit. (more)