It has EVERYTHING to do with the frame rate. I can very rarely tell the difference between a still taken with a professional digital camera, and a still taken with modern film stock. The same is true with motion pictures. When I saw Get Smart for example, I didn't know it had been shot...
My own estimation is that around 95% of the "film look" comes directly from the 24fps rate. Shoot the same action, with the same camera and settings at 24fps and then at 60fps, and the different is noticeable instantly by almost everyone who sees it. I've done this experiment myself and it...
Given the fact that the Hobbit preview at 48fps has gotten rather negative reactions from those who have seen it, I'm not sure there is much future for higher frame rates. At least not for narrative film making.
Doug