Not to nitpick, but the answer to your posit is addressed in the site's FAQ. As they pointed out, a touchpad mouse simply follows the midline point of presure applied to it. What makes they're product neat (worth $179 I am not sure about... I'll get back to you on that after I give it a try) is that it actually monitors your entire hand's location in relation to the pad. This allows the pad to use specific motions to control repetitive events (such as saving files, opening files, scrolling, they even have a pre-defined emacs motion set)
This product is not intended to be 'just another kind of mouse/keyboard' but an entirely new type of computer interfacing.