This is in the concept phase, but it looks pretty interesting. It may not look immediately necessary, but if you are traveling and you family has more than one iPhone between them, there may actually be times when you need to give someone some juice to keep their iPhone going. Here's an example where this would have come in handy:
A few weeks back I was letting my iPhone drain completely. We went to visit the girlfriend's family, and the dog, a giant bloodhound, had found a way to escape from the back yard. We decided to help track down the dog. Unfortunately, I had somewhere around 20 percent battery on my phone. I hadn't anticipated anything like this, and all we were going to do was eat lunch. Easter lunch became find the family dog. We each had took a route, and I was stuck with 20 percent battery and didn't have my charger with me. Perhaps keeping this in the girlfriend's car could have meant enough of a charge to keep my phone going for a bit before splitting up to find the dog. At the very least, I could have used my girlfriend's iPod touch as a power source for the time being. Oh well, I'm happy to report that the dog is fine and has become a big indoor dog since.
Here's how it works:
This isn't designed as a way to fully charge your device, but it will get you by in a pinch. It's just an App and you connect your devices wit Apple's connector. Again, it's all a concept at this point.