CNET had the opportunity to test Tobii's eye control interface for Windows 8, you can read about their experience over here.
I sat with Barclay and Tobii's Anders Olsson at CES today and got to try the latest from Tobii. One of the key tenets with the Windows 8 demo is that it uses a combination of touch and eyesight for the interface. To select a tile to launch, for example, you press down the Windows key, look at the tile for the app you want, and then release the key. That ameliorates the issue of having your computer go off and do something when your mind or gaze wanders. It is easier to look at something on a screen than it is to mouse over it, in terms of actual speed and effort, so this should work.
Tobii works by shooting near-infrared lights at your eyes, and then uses two IR cameras to capture "the reflective point of retina plus the glint off the cornea," I was told. From this it builds a 3D model of your eye. Tobii requires new hardware compared to the cameras in PCs now; I saw the demo on a custom-built machine that used to be an HP laptop. No word yet on what the premium will be for the technology. When touchscreens first came out on laptops, the premium for that technology was around $200 to $400.