Nokia has come up with technology that converts radio signals into electricity, and at the moment it's just enough to keep your phone from going dead. A fantastic idea, and I'm surprised it took this long to figure out. After all, we've been converting electrical energy into radio waves for over 100 years.
While "traditional" (if there is such a thing) wireless power systems are specifically designed with a transmitter and receiver in mind, Nokia's system isn't finicky about where it gets its wireless waves. TV, radio, other mobile phone systems -- all of this stuff just bounces around the air and most of it is wasted, absorbed into the environment or scattered into the ether. Nokia picks up all the bits and pieces of these waves and uses the collected electromagnetic energy to create electrical current, then uses that to recharge the phone's battery. A huge range of frequencies can be utilized by the system (there's no other way, really, as the energy in any given wave is infinitesimal). It's the same idea that Tesla was exploring 100 years ago, just on a tiny scale.
Right now they're only able to pull 5 milliwatts of power from the air but that will improve over time. Estimates are that the technology will be available to the consumer in three to five years.
Can't wait until they figure out how to power an electric car in the same manner.