[dirtbox]

I use ZBrush to create displacement maps using HD geometry, which doesn't use actual polygons in the classic sense. A lot of the ultra high poly models you see on the turntables and such use the same technique. You can easily make a mesh well over a billion polys that doesn't impact the system. http://www.pixologic.com/docs/index.php/HD_Geometry

I doubt they'd have anything anywhere near ZBrush's flexibility and depth.

[windsurfer]

You could totally take a displacement map and tessellate a model with it. In fact, that's what OpenGL4 and DirectX does in hardware.