Completely correct. This is not a new idea at all. However TalkingLights had a huge bandwidth limit because they used flourescent lighting.

LEDs can go to much higher speeds - but even still, this isn't new. Researchers in Japan and Boston University have been producing demos for years:

http://www.bu.edu/smartlighting/research/smart-light-prototy...

http://www.naka-lab.jp/index_e.html

Much much older than that: http://www.alge.no/ebooks/Optical_tempest.pdf

This technique was used in at least the early 90s