The app isn’t quite as open as the web interface (you can’t just upload your own 3D files), but it does allow you to create custom 3D objects like pre-designed mugs, vases, or even iPhone cases, then customize those things directly from your phone. Created items usually cost from $30 to $40; once created, iOS users can order items right from their devices with immediate shipment.
The idea of printing my next iPhone case from my iPhone sounds cool to the geek in me. I am also keeping an eye on MakerBot which just announced their new Replicator model. 3D printing is coming and it is going to be a big deal.