GM's working on a system using data gathered from vehicle sensors and cameras to project compact ultra violet laser-generated images directly onto the entire surface of the windshield. It's sort of like they're bringing the world of Tron to you.
Look at this like a next-gen Head-Up Display (HUD) system. Coated with a series of transparent phosphors emitting visible light when excited by a light beam - in this case from a compact laser - the windshield becomes a large area transparent display, instead of current reflective-light HUD systems that use only a small portion of the windshield.
The ability to use the entire surface enables the system to alert drivers of potential dangers that may exist outside of the normal field of vision - like kids playing next to the curb or a Lotus Exige pulling up alongside a Chevy Suburban.
On a foggy day enhanced vision system could combine night vision with the head-up system to identify and highlight the precise location of the edges of the road with a Tron-like neon line, or animals roaming along the side of the road as a big, neon-colored blob.
No word on when, if ever, we'll see this type of technology on GM vehicles, or what it'd cost or how much weight it'll add. But, hey, it looks cool, right?