Arqball Spin is a strangely-named iOS app that does something pretty magical: It will create fully spinnable 3D models from real-life objects. The app is available to download right now, so you can go and check it out for free. Engadget played with both the app and a stage (more on that in a second), and they have examples and video of how the app works. The model looks pretty great, even just viewed in a web browser.
Basically, the app uses your iPad to take a series of pictures of an object, and then assembles those pictures into a "rotatable" model, essentially faking 3D (sort of similar to those old shots from The Matrix, where a series of cameras took a sequence of rotational photos that were then stitched together). The catch is that obviously all of those photos need to line up as exactly as possible. While (presumably) you could just hold your iPad in place, you'll get a rough result that jumps around in the frame, unless you get exactly the right angle every single time.
To counteract this, Arqball is selling "stages" over on Kickstarter, which precisely holds and rotates your object. If you don't want to get involved in the Kickstarter (or just outright buy one after it's been funded, for $80 rather than $60), you can even make your own stage, as long as it rotates your object at the right speed.
At any rate, it's a great idea, and it could mean some big things for 3D modeling in the future. We've also seen the iPad used to create 3D models that can then be printed, so someday, you might take a series of pictures of an object with your iPad, and then hook that up to a 3D printer to get a copy of that object for yourself. Very cool indeed.