This guy may be on to something. When I first plant my hands on the keyboard to start typing, the first thing I do is feel for the ridge on my 2 home row keys to make sure I'm on center without having to look down first. Same goes with the numpad, I make sure my middle finger feels the ridge on the 5 key first so I know I'm centered. If you could *feel* each key, then you'll get a more positive notion of not second guessing yourself if you you think you over reached a certain key. Also, I'm not terribly great with symbols on the top row of numbers, but if I could feel them I m would not have to always look down.
Anyway, he may have glued them to an existing keyboard, but as the article states this is a prototype and I imagine that if interest peaks, he could do his own fabrication and include different keyswitches and layouts.