Brilliant, let's not get bogged down in trying to model 3D objects with the limited CPU of the iPad, but use it as a control interface for software running on a networked computer.  Beautiful Modeler by Interactive Fabrication even uses the iPad's accelerometer to control the rotation of the object, very cool. 

Beautiful Modeler and the Beautiful Controller were created using openFrameworks. The finished mesh can be exported as an STL file (thanks to ofxSTL), meaning the sculpted form can be fabricated immediately. In the video above, the positive mesh has been post-processed to create a negative form for fabrication with a plaster-based 3D printer.

Interactive Fabrication showcases projects exploring Interactive Fabrication: interfaces and devices that take real-time input to fabricate physical form.  They are Karl D.D. Willis, Cheng Xu & Kuan-Ju Wu collaborating with: Golan Levin, Mark D Gross, Juncong Lin, Jun Mitani & Takeo Igarashi.