Am I the only one that thinks this could be some sort of eye recognition? have your eyes be the mouse cursor and press a button on the back side of the slate to confirm a click. Add voice command use instead of a keyboard (but with virtual keyboard as an on/off option) and we're talking the next step here! If anything it'll greatly reduce smudges on the screen lol
I don't know if the cursor would ever be directly tied to your gaze, but given Apple's patents on interface interaction through gaze vectors and facial expressions, something like this could be entirely possible. That would require some learning.

Article Link: Beyond Multi-Touch: Voice, Gaze, Facial Expression Recognition