This is an item I would not be surprised to see in RAC 2012 or 2013....Nucleus is a Maya based modeling tool that is starting to be incorporated into Revit. For all of those who remember the massing overhaul a few years back, this transformation makes that look rather generic and archaic.
Granted, with a background in engineering this does make me cringe when I try to imagine all the new non-squared designs that will potentially evolve if this is pushed to be included in the OOTB Revit release. Nonetheless, this still seems like a REALLY cool tool developed and AutoDesk is allowing you to play around with it until the end of this year.
This also does have great potential on the engineering (structural) side as well with its proclaimed ability to simulate loading conditions. Their website says that it has the ability to display gravity, wind, and collision loadings, but I think where this could have a greatest significance in today world, if accurate, is with blast and seismic scenarios.
Though it does state that designs made with Nucleus will still function after the trial expiration date, I would still be wary of overhauling your library before (if) this becomes standard OOTB with Revit.