A bit from The Labs' description: "Project Nucleus integrates the Nucleus simulation engine from Autodesk® Maya® into Autodesk® Revit® and Project Vasari. It allows designers to experiment with "form-finding" in the conceptual design phase by simulating forces directly in Revit and Project Vasari. (An upcoming technology preview of Project Vasari will include the Project Nucleus functionality.)
Project Nucleus can simulate a wide range of physical phenomena in real time, like wind, gravity, constraints, and collisions. These forces can help architects generate free-form shapes, many of which would be impossible to model by hand."