Any mechanical engineer who's had to take a 3D object and model it in CAD will love this.
I've been toying with the idea of such software in a phone for a while but never bothered exploring it because I lack the technical chops. There's a piece of software I've previously used called PhotoModeller [1] that allows you to calibrate a standard digital P&S camera then use a bunch of shots of the scene from various angles to build a 3D point cloud of it. Given that you can know the lens of an iPhone to a pretty close accuracy, I was thinking that you could build a similar application straight into the phone that then could upload 3d scans to dropbox. It'd be invaluable to field work.
This takes the above idea and loads it with steroids. I'm really excited!