Coming this spring from Mophie is the Juice Pack Air for the iPhone 3G, which is essentially the Juice Pack but with a top cover to fully encase your iPhone. I’d be excited by this concept, but I’ve been using FastMac’s iV for the last month and it’s significantly better despite it’s girth.
Mophie touts this as being the world’s thinnest Apple certified “Works with iPhone” external battery, but the Air only has a 1200 mAh battery and that pales in comparison to the iV’s 3100 mAh battery. At this point I’m more interested in battery life than looks. However, I can’t cram the iV into my pocket and that’s a problem. On the other hand I have two broken Juice Packs on my desk.