Will, you'd have to have the deep edition with animation features. Simply create 3 frames, with a key frame on frame 1 and frame 3. Then, you simply render just frame 2, which will have that motion blur effect because your camera is moving from the position on frame 1 to the position on frame 3. That's it.
It's not like mrwho suspected, that the stones where moving, that's not correct. The only thing moving is the camera.
Cheers,
Frank