I think we'll be seeing more solar powered devices in the coming years. e-Paper based e-readers hardly use any power (hence the months of battery life on the devices!), so you don't need THAT much juice to power it up.
I've been reading the news that some major LCD manufacturers are combining TFT technology with solar technology, so your display will actually double as a solar panel. It's amazing!
http://news.softpedia.com/news/AUO-B...e-230853.shtml