I think you guys are wrong. I have a wall plugin usb charger and it works fine. I think I bought it for that very reason so I could charge my Clie' without plugging it in to the computer. A usb cable provide a 5 volt power source for the attached device. This is what is used to charge the battery.
USB connector pin assignments:
http://www.google.com/imgres?imgurl=...num=4&ct=image