It sounds like the poster boy (or product) for “have your cake and eat it too”: Third Rail Mobility‘s new backpack-battery system is a slim case (callled the Slim Case, just to be confusing) that allows their removable 1250 mAh Smart Battery to snap on. Smart? Heck, the battery sounds like a genius: Besides being able to power other electronic devices off its micro USB port, “stacked Smart Batteries will automatically and seamlessly transfer power to create as many fully-charged batteries as possible,” says the press release.
The whole kit runs $90, or the case and battery can be bought individually for $40 and $60, respectively. And right now, it’s only available for the iPhone 4 (Android flavors coming soon).
