Incase released an upgrade to their popular Slider case for the iPhone. The Incase Power Slider ($100) is a first of its kind case that is integrated with a supplemental battery. The durable, lightweight hardshell with soft-touch coating includes a rechargeable lithium-ion polymer battery that more than doubles the battery life of the iPhone 3G. The design has a built-in five light LED battery status indicator and is compatible with the USB charging port. The Power Slider not only offers protection but also doubles the battery life of your iPhone 3G. [via Boing Boing Gadgets]