This is brand new.  Here is the description from the iSound website.

Shipping is free within the US.

The stylish leather Power Case protects and powers your iPhone 3G/3Gs with a built-in rechargeable lithium-ion battery capable of providing up to an addtional 36 hours of audio playback, 6 hours of video or 3.5 hours of talk time. Compatible only with iPhone 3G/3Gs.

Product Features:

* Compatible with iPhone 3G/3Gs
* Built-in rechargeable battery charges and powers iPhone 3G/3Gs
* ON/OFF switch lets you decide when to activate battery
* Stylish and protective leather flip-open case with magnetic closure
* AC Adapter included
* Input & output: 5V/500mA

* NOT COMPATIBLE with iPhone 4