This project is essentially the same as the Portable Zune Charger listed in the Completed section, with one exception. This charger uses a solar power to provide power at approximately 7.5volts, which is then lowered to 5v by the same assembly of 78M05 voltage regulator, .1uF tantalum capacitor, and .47uF electrolytic capacitor listed in the other thread. Once the female end of a USB cable is attached, the assembly provides power to all manner of USB devices, but is not recognized by the Zune. To fix this and see the happy little charging icon, use a 15k ohm resistor with both data wires of the USB cable connected to one end and the output of the voltage regulator assembly to the other. I found this information in a thread at ZuneScene, in the thread titled DIY Wall charger. I would post links to all of this info, but i can't yet.
Any questions, comments, complaints: logiasin AT gmail.com
Unfortunately, it's not airport-security-friendly, due to the home-made look with loose wires and stuff, and I'm about 1500 miles away from it right now. When I get back home, I'll be more than happy to show some pictures of the completed assembly. Keep in mind this is my 2nd application of my soldering skills, so its not very clean... :-/
it sounds like a awesome idea, but i feel like you won't be able to get enough power out of a solar panel that would be small enough to be portable
You could make the length and width of the panel a little bigger than the zune, have the zune rest in it, and have the panel fairly large in depth. You can have this sit down in the sun when you are in the car, or anywhere else.