Now this is an interesting one.
It appears that Apple have filed a patent application that suggests they may be looking at ways of using the screens of their mobile devices as solar cells in order to recharge themselves in daylight. In the past adding a solar panel to a mobile phone was unattractive because it added additional bulk (I just bought an external solar charger to keep my phone going during the Summer festival period) but it seems that Apple have invented a way of integrating the solar panel beneath the LCD screen.
This could be a pretty cool step forward in keeping mobile devices, that are Wi-Fi'd up, working a whole school day.
My info at:
http://www.macrumors.com/2008/05/26/solar-lcd-powered-ipods-iphones-and-laptops/