Apple has filed a patent for a full range of media players with integrated touch sensor solar panel surfaces. The recent design change for the iPhone from a metal backside to a glass back would allow for an internal double-sided solar panel. This makes it obvious that Apple is moving in the direction of integrating solar cells.
The patent shows that the solar cells would charge the rechargeable battery, which will run the media player or the battery can run the media player directly.
Great news, Mr. Jobs!