Knock 3 Times on the Ceiling (to Turn on the DVD Player)

The New York Times > Technology > Circuits > What's Next: Knock 3 Times on the Ceiling (to Turn on the DVD Player): "French physicists have figured out how to rap on tabletops to communicate with CD's, lights or most other nearby electric or electronic devices."

I see this going in one of two directions:
1. Either it revolutionizes consumer electronics interfaces, or
2. It's the successor to The Clapper