As I mentioned above, you
need to be careful with these 3rd party chargers.
According to Apple's support site, the "Apple iPod Power Adapter" ( with firewire or USB port) outputs 12V at 1A, which clearly violates the USB power spec.
http://support.apple.com/kb/HT2537
I don't know if this is the exact same charger mentioned previously in this thread (it looks a little different), but you need to be sure what the power output is before trying to use these on devices that they weren't specifically designed for.