Google may be reviving the idea of the projected keyboard as part of its Project Glass.
A patent application suggests that the company is playing with the idea of integrating a projector into the device with the capability of projecting a keyboard on any surface in front of it, such as a user's hand. Conceivably, you could use one hand as touch screen surface and the other to type. Sensors would be employed to measure the distance of the surface and translate hand movements into keystrokes.
The idea of projection keyboards has been around from some time. IBM holds the patent for the original keyboard, which was granted in 1992. However, the most convincing implementation may be Canesta's optical keyboard that was first presented in 2002, but never made it into the mass market. Canesta was able to license its technology and was briefly rumored to be acquired by Microsoft and help Microsoft to provide virtual keyboard technology for Kinect. However, Canesta is still operating on its own and has abandoned this market segment.
A Mozilla Labs project from 2011 also played with the benefit of a touchscreen by conceptualizing a smartphone with two projectors - one for projecting the content of the small display on a large screen and one to project a keyboard on a surface.
What makes such a keyboard very interesting is the fact that the sensors can react quickly and typing via a laser-assisted keyboard can work without the input delays we know from touchscreens.