Something that's a standing desk/tilted drafting desk form factor combined with good palm/elbow/forearm recognition would immediately address the "gorilla arm" problem with such interfaces. Combine that with Reactable-style tool objects, and input from cameras and/or a Kinect, primarily in order to make the system "smarter" about how to interpret touch, and I could see some really revolutionary interfaces for applications that are amenable to a data-flow style model.
(Applications where you have boxes connected by pipes/arrows to other boxes.)
(Applications where you have boxes connected by pipes/arrows to other boxes.)