Sheathing something as slick and pocketable as the iPhone in a holster feels wrong to me for many reasons, but this particular holster adds the handy ability to charge your drained batteries with its own rechargeable Li-ion battery back. It's good for one full charge before it needs to be recharged itself. Handy, and at $25 the price is right, but this thing is huge. Product page says this only works with first-gen iPhones and iPod touch-but I don't see any reason why you couldn't squeeze a 3G in. [Product Page via BBG]
@DisposableInterloper: The fanny pack never actually went away. They can still be found nestled under belt line-spilling rolls draped in brightly colored striped polo shirts above odd-fitting cargo pants, probably holding several versions of the subway map, and a cheap cricket cell phone.