Re: Push Push Push.
Perhaps these free-space gesture systems work better for some tasks than others. At the very least, even just enough functionality to allow users to put down their mouse periodically might help reduce RSI. (And from what I've read of reviews of the similar-ish LeapMotion device, the converse is true; it can also be tiring to use gestures for extended periods too, but at least it is using different muscles)
Personally, as a (Mechanical) CAD user, I'm waiting with interest to see if anyone develops a natural control 'grammer' for these 3D human input devices. Even on the 2D tasks, I'm impressed by how civilised the UI of some CAD packages are (they let the *user* choose to use keyboard shortcuts, customisable toolbars, 'Ribbon'-like menus or pie menus, in addition to providing the resources needed to let strange peripherals like the SpacePilot work with them).