We’ve heard of Google glasses. What about a digital windshield?

We’ve heard of Google glasses, and digital dashboards. What about a digital windshield? Wonder if anyone is working on that. Seems to be an easier first step. Think of it. We could eliminate physical road signs – they would just appear in the windshield glass, like the Wild Animal warning sign in the image. Don’t bother building a GPS screen into the dash – just put it in the windshield, easier to keep your eyes on the road. I imagine these images would be translucent. Of course you would be able to move them around with your fingertips. Downsides: the road signs would not be available to cyclists, lots of clutter in the screen, perhaps too distracting.