Mophie has introduced its Juice Pack Air, a thinner, more case-like version of its Juice Pack external battery pack for the iPhone 3G. The Juice Pack Air features a rechargeable 1200mAh lithium polymer battery integrated in a hard-shell case. The Air will also feature pass-through USB charging and syncing, an on/off switch, a 4 LED charge status indicator, and a slide-together design. Premiering in black, white, or purple, the Mophie Juice Pack Air for iPhone 3G is available for pre-order now at a price of $80, and will ship this spring.