I've been watching this from the public announcement date, preordered, applied for dev sdk, and been active on the forums, as well as pondered the possibilities (read, waving hands in the air a lot).

In my conclusion - THIS WILL REPLACE TRACKPAD.

Not augment, not be by the side of. REPLACE. And not only because Leap is awesome, but because trackpad is horrible.

EDIT: You'll remember not upvoting this one when you're proved WRONG.