[48snickers]

I imagine there's plenty of prior art supporting invalidating the Hillis patent, if it came to that.

For example, 1997: http://tangible.media.mit.edu/project/metadesk/

1:30 in the video seems to show the behavior described.

[abecedarius]

Yes, when I tried out Hillis's touchtable around 2005 my reaction was like "Cool! I'm finally seeing this kind of thing in person."