I don't think people are grasping what this could do or how it could be used.
Imagine one of these embedded where the current trackpad on mac laptops are.
Now place your hands as if you were using the trackpad. Perhaps the palm of you hand is resting on the edge of the computer, perhaps slightly to the side, perhaps on a table or palm rest right in front of your laptop.
Notice, your arm is completely supported. Now raise your fingers from the trackpad an inch or so. That's the position most people rest their fingers in when they don't want to touch the trackpad, right? Just hovering over the trackpad?
Ok, that's the position you'll use a leap motion in. Same basic position you use a trackpad in, but now you get one extra dimension, and you never need to touch the device.
Kinect is a low resolution device. That's why you need big arm swings to register movement on a kinect. Check out the video for this thing though. It looks incredibly accurate and it picks up very small moves. You won't be waving your arms around, you'll be wiggling your finger(s) around. You won't need to point to a physical location on the screen, you'll have an abstraction of the screen near your keyboard, the same way trackpads now abstract the screen onto a few square inches.
In fact, they could build this thing 'under' the keyboard, eliminate the trackpad entirely. Want to control it? Just lift your right index finger from its position on the keys, pointed to the screen and wiggle it left right, up down.
In a way, it returns us to the IBM trackpoint days, where you could use the mouse without leaving the home row, but with more flexibility, a larger 'canvas', multitouch, and 3 dimensions. We shouldn't need to take our hands off their position above the keys to use this, so it makes it better than current trackpads/mice.
