I am a little proud to say, I suggested this in 2005:

"There has to be at least one unique feature. I suggest some sort of projection display that allows you to project (for maybe 5 seconds at a time) what is on your screen to any reasonably flat surface like a wall. This would allow you to show your buddy or boss a document or a picture. An inexpensive LED bulb or two plus the ability to project 640×480 if that, is all that is needed."

Comment #6, here: http://blogs.law.harvard.edu/philg/2005/09/23/could-a-mobile...