First came Fog Screen (http://www.youtube.com/results?search_query=FogScreen) (via tiny water particles -- so you can walk through it (http://www.youtube.com/watch?v=46IzFJW1Svg))
Then Helio Display (http://www.youtube.com/results?search_query=HelioDisplay)
Now: Displair (https://www.youtube.com/results?search_query=Displair), "the Air TOUCH System" (it uses a smaller steam-generator along with a projector and some infrared sensors, to allow for more control including "touch" interactivity).
(more demo'ing of the tiny, PORTABLE DisplAir, by the 24-year old inventor (http://www.youtube.com/results?search_query=Maxim+Kamanin) himself @ http://www.youtube.com/watch?v=MHdcA2InruA )
http://displair.com/product/