well this is very cool stuff...
the idea here is that the device is kind of circuitry that harvests the WiFi energy out of the air and convert it to electricity.
The device(Airnergy) has a small battery in it, so you can just carry it around and as long as there is a WiFi near you, it charges itself.
The great news is the device will be out in the market soon for 40$ !!!
for more info check that blog
