Our research lab recently created a more involved version of this using fairly cheap materials that's much more expressive:
http://www.cs.columbia.edu/CAVE/projects/3d_display/
(Don't miss the video at the bottom of the page.)
http://www.cs.columbia.edu/CAVE/projects/3d_display/
(Don't miss the video at the bottom of the page.)
The link says this was created in 2006/7. Have there been any advances since then in terms of resolution, or otherwise?
What I found especially interesting is that even though the point-etching in the cubes is static (and of a generic head), faces are mostly similar enough (and the animations required for speech small enough) that looking at the animations actually looks very realistic in person.