You'd have to leave your phone lying around in pretty much direct sunlight to get an power at all. There's almost no space on the front of the Desire for solar cells. And i'm about to completely make up a statistic here, but I'm pretty sure that even if the whole of the display of the Desire were made of solar cells you'd probably need 4 months of sunlight to power it for even a few minutes. Having solar cells anywhere other than the front would mean people would scratch their phones to death turning them upside down on rough, outdoor surfaces, and you'd have to watch them the whole time otherwise they'd get stolen. I don't think there's much power to be gained from internal lighting. If you're inside, you're better off just plugging the phone into your PC or the wall.
Ditto for using kinetic energy - charging your phone as you walk.