Like i linked couple of pages ago Nokia demoed their "haptikos" on 700 and N800 in 2007 and back then people where expecting it to be inside the iphone fighter(that came to be 5800.... ). You got liquids inside the phone that raise the screen 0.1mm to form tactile buttons. People that tried it where surprisingly positive back in 2007 already, but i can't see how it works on capacitive screen.