Is that really how the regulation works? If I don't put any information in the signal, I can use all of the power that I want?
According to the article referred to by this Slash Dot story, the received power is on the order of microwatts, while the camera requires milliwatts. Because of this, you need to wait many minutes between camera frames.
I think that if we are going to broadcast noise for the purpose of powering gadgets, we should dedicate some unused spectrum for this and not interfere with existing signals.
On another subject, I used to live within sight of a 50,000 Watt AM radio station. The signal used to get into the band's amplifiers. I bet that you could power a lot of gadgets from that monster.