Is there any reason IS couldn't be implemented in software? You could produce a 5MP image from a 6MP sensor by using the extra pixels to shift the image. You'd need to measure the movement of the camera, which could be done using a sensor of some sort in the body, or could conceivably be done by measuring the movement of the image on the CCD. This could mean that IS could be added to the *istD by a firmware upgrade.
This is all speculation, and I could be talking rubbish. Any comments? Nick

