Quote - Well, we know that the Material Room is Pixels3D all the way! ;)

A-ha, then I imagine they based the renderer on Tempest as well, being that seems the most efficient thing to do.

Yes, a quick google search brought me to this page:
http://www.keindesign.de/stefan/poser/firefaq.html#10

The renderer is a "sibling" to the Tempest renderer.  The shading system is akin to ShaderMaker Pro.

Edit:  apparently, this information is no secret.  It's stated clearly on the box and documentation in Poser that they licensed the Tempest engine.