Virtual Keyboards are close to be available on the market.

Israeli based VKB Inc. shows off their Virtual Keyboard at the CES in Las Vegas last week. The unit is available as stand-alone or integrated like the one in the photo.
iBIZ Technology is distributing and marketing the Virtual Keyboard in the United States.
The Virtual Laser Keyboard leverages the power of laser and infrared technology and projects a full-size keyboard onto any flat surface, as the user types on that projection; it realizes what you're typing by the coordinates of that location. Unlike many small snap-on keyboards for PDAs, the Virtual Laser Keyboard provides a full-size QWERTY keyboard. Not to mention looks bloody cool using it.

The Virtual Laser Keyboard is compatible with Palm, Pocket PCs, laptops and desktop PCs. The keyboard employs a USB/serial cable connection to communicate with the PDA or PC.
An upcoming version for cell phones will be available in 4th quarter 2004. The Virtual Laser Keyboard will be available for $99.99 from major retailers, e-commerce sites, and iBIZ Technology's own e-commerce site. The site states that the Virtual Keyboard will ship early February.