I bought one of those black and decker pocket batteries, mainly because it was free with google checkout.

well I went and tried to use it to charge my touch, and nothing happened. I go and try my brothers 3g ipod and it charges just fine.

the only thing I could figure out was that there are no data pins on the battery side usb socket. I thought that is rather dumb, and makes my battery pretty useless unless i also haul around the ac-dc adapter for the ipod.