I've seen this sort of thing done with one or (more commonly) more projectors. There's some really cool software that does the edge blending too. One problem with doing multiple surfaces with one projector is that you may not be able to achieve a good focus if they are too far apart, or on too much of an angle to the projector.
I wonder how bright it actually is or is the camera making it look brighter than what it would really appear in real life. I think one very important thing here is the colour of the surface he is projecting on which is white so would allow for doing projection a lot easier. I do love the idea of projection and would love to eventually incorporate it in my display
first thing you need to do is find time to program such a thing. One thing this guy has suggested is rip up all you lawn and lay rock down, that way you no longer need to mow plus it is a free secruity system as you know when someone enters your property. lol