Somehow, I don't think the world is ready for a charger that powers up an iPhone when you flex a hand grip. I mean, a firm handshake commands respect, but we are still talking about exercise here. So, I think that a solar powered charging case is probably about as eco-friendly as most of us are willing to get. On the other hand, you could view it like a stress reliever—a means of squeezing away your frustrations. Based on the time displayed on the iPhone in the image, my guess is that the designer also had stress relief in mind with this concept as well. [petitinvention via Ecofriend via Gearfuse]
It'd sound pretty useful if I could use it on my Ipod. I have very little hand strength, so my writing looks like something you'd expect the Joker to scrawl on paper, and it'd make it easier to keep the blasted thing up and running without having to deal with all the glitches if it loses too much power.
And of course watching me give it enough power by making a cycle of listening to something like "Blow Up The Outside World" by Soundgarden, fuming about my current luck in life, and transferring stress by squeezing the crap out of it is always good for laughs!