Now I don't have an iPhone, but I hear from people that can afford one that they're not great when it comes to battery power. Well, that's about to change with the November 28 release of the Powerslider, a case for the iPhone 3G that also doubles as a power source. 

It has a built in custom engineered lithium-ion polymer battery that is the first point of contact as far as power is concerned, and once that source is gone, it then begins to draw power from the iPhone’s battery and operates off of that.

[Incase] [Via SlamxHype]

Related: One-Upping the iPhone