Computerworld: User interfaces of the next generation
..a technology that lets users of PDAs and similar mobile devices put data into their handheld systems by simply typing on an image of a standard-size keyboard projected onto a desktop or other surface. The "electronic perception" technology captures the user's finger motions via emitted light photons that form 3-D real-time images that are then processed and translated into keystrokes.

..projection keyboard heralds the way to much more powerful user interfaces that are based on hand gestures. You could open up a filing cabinet and pick up a file and sift through it with your fingers, using gestures from your hands as if you were actually picking it out of the file cabinet.

This technology is not about replacing the keyboard and the mouse but to supplement them. In 20 years, gesture technologies will be as common as the mouse.