Forget about the AC charger that comes with the solar battery linked above - it puts out about 200mAh, which seems too low even for the Clip. Charging with the solar battery works fine however. Due to the bad weather I wasn't yet able to test the solar panel, but the high capacity battery comes handy when you're travelling and need some spare power for your DAP/phone.
I ordered another model, this time it's supposed to have 2700mAh for a price of 8€!.. When I have both here I'll test them more thoroughly (I have to find some way to measure the battery's real capacity, any ideas?).