3D touchscreen for mobiles

Just how did Nintendo manage to make a 3D screen for their latest console, to be released within the year, and how come this technology didn't make it to mobile phones first? Sharp has announced that it too has developed a 3D touchscreen for use in mobile devices. So how does it work? Vertical slits built in to the screen can be controlled, changing the direction that light leaves the screen, so that one eye sees one picture, and the other eye sees the other, creating the illusion of depth, simples.
Source:unthinkable