>More of the problem is that it doesn't work room to room, only line of sight like with a remote control.

If you could cheaply make the lights transmit and receive, and if the data were recoverable at very low illumination, you could employ mesh routing -- there's often quite a bit of overlap from lightbulb to lightbulb.

But you're correct -- answering the LoS problem is significant. This could be very useful in many applications, but it's no silver bullet.

While the LoS aspect is potentially desirable in specific applications, I agree that initially it can be perceived as a limiting factor. Researchers at Boston University,Rensselaer Polytechnic Institute, and Nakagawa Lab in Japan are working with software tools to characterize non LoS applications using reflective and refractive surfaces found indoors. A powerful system can be envisioned if someone managed to utilize these principles with a device that contains a receiver with a wide view.

Or you have a "networked" light socket in each room and a discovery protocol to figure out what room to route the data to. More work on the initial infrastructure side, but then you don't have to worry about mesh- your room is covered.

You'd network your light sockets to get around the room-to-room issue. Each room would have a light bulb "port". Some simple communication could then figure out which room your in (similar to access-point hopping used in large wifi distributions)

I can see this as a potential technology for sideband data: stream the video over the light, but the control data would still go through WiFi (and then you wouldn't bog down your wifi with torrent downloads)

Yeah, I think so. So now you have to wire your house with a wired network, and when you want to watch TV or use your computer you have to turn the lights in all the rooms on.

A simple CDMA or TDMA (code/time division multiple access) scheme allow multiple devices to receive/transmit at the same time. This is how cell phones work.

See: http://en.wikipedia.org/wiki/Code_division_multiple_access