Originally posted by ffking There are rumours about Canon revisiting that, but the fact that they haven't yet might be siggnifcant in terms of user uptake or real world usefulness - or it might not be
As cool as eye-controlled focus sounds, it's not very compatible with how human vision works.
People's eyes are constantly in motion, twitching over different parts of the scene about 3 times per second. It's kind of like panoramic tiling with a telephoto lens and it's how human vision builds up a detailed view of the world. That's especially true of photographers who might be (should be!) checking all the other non-subject elements in the foreground, background, and borders of the photo.
Although the camera can follow the photographer's eye, it can't read the photographer's mind to know when the eye is looking at the subject or is looking elsewhere in the scene. Thus, a eye-controlled AF system would tend to jump all over the scene as the photographer makes these unconscious eye movements.