Wysips, a company based in the south of France, developed a thin transparent photovoltaic film that can be used to charge smartphones, e-book, tablet and even laptop. They were at CTIA 2011 and were interview by laptopmag.
Their transparent photovoltaic strip is 100 micrometer thick and can be used with touchscreen and 3D displays. It can provide 250mW for smartphone by continuously charging the device (6 hours of outdoor light) and possibly removing the need for charger. The cost for smartphones would be 1 USD, which could potentially be offset by a smaller battery. They are currently working with handset manufacturer and expect products using their technology to hit the market within 12 months.
The next version due in 2012 should provide enough power for 30 minutes of talk time after one hour of charging.