Nice little gadget! Actually i was embarking on a small project from instructables.com using the 9V battery as source. Have got all the components, but currently lacking a female usb socket. My local electronics sold every component i needed except the usb socket. Guess i'll look around for some cheap usb hub where i can remove the socket to use it.
Will post a thread if i do manage to get 1 working, provided i find a usb socket.
But this USB Battery Pack, is a definite must-buy this christmas!