While attempts to add feedback to touchscreen displays via vibration and audible tones are laudable, these attempts are nothing by comparison to the tactile euphoria felt at the press of a well-designed button. Still, many of us are willing to sacrifice tactility in order to maximize display sizes on our pocketable or portable devices. Now researchers at Carnegie Mellon have developed touch-sensitive displays with physical buttons that "pop-out" from the surface. CM's prototypes pump air through geometric-shaped holes to create concave or convex "buttons" on a screen covered with a semi-transparent latex -- IR sensors and cameras detect finger placement while a projector cast images (like numbers and graphics) onto the display. It can even sense press-force by monitori
