Nokia is already working on the next step... a phone that powers itself:
"A new prototype charging system from the company is able to power itself on nothing more than ambient radiowaves – the weak TV, radio and mobile phone signals that permanently surround us. The power harvested is small but it is almost enough to power a mobile in standby mode indefinitely without ever needing to plug it into the mains."
http://www.guardian.co.uk/environmen...a-mobile-phone