Originally posted by Digitalis That was sort of where I got the idea from. As I had the pleasure of owning a Contax AX, Aria, RTSII and III - I really liked those cameras I consider the Aria to be my favourite camera from the late 90's. For those who don't know the Contax AX used ceramics to control the travel of the focusing mechanism ceramics were used ensure the longevity and precision of the focusing mechanism, which was itself powered by an ultrasonic motor. Though the contax AX had a limitation: film plane could only move back and forth by 10mm. A digital sensor is inherently flatter than film is, so film flatness issues are no-longer a problem. And having a sensor on a moving platform also would be a real boon to macro photographers. Hypotherically speaking If we had around 20 or 30mm of travel for the sensor even an ordinary 50mm lens it would be quite possible to get around 1:2~3.5 magnification and with dedicated macro lenses it would be possible to get even higher magnifications. With a camera like that you could eschew pentaprisms and go completely EVIL because the focus could be based on contrast detection from the sensor itself.
I see a few disadvantages with this type of design.
I wanting to keep sensor stabilization it will be a pretty big and heavy part that has to moved inside the camera.
By adding 20-30mm to the thickness of the camera you probably end up with a camera bigger and heavier than a DSLR.
One of the biggest advantage of EVIL is that by removing most complex mechanical parts manufacturing cost is lower, and quality can be kept higher. This will be lost if adding an even more complex mechanical design than a DSLR.
There might be a small market for a camera like this with FF sensor and optimized for manual focus lenses, but it probably end up with a Leica M9 price tag.