mental images has integrated their own Shader Language named “MetaSLa” into mental ray 3.7, which should make optimization of shaders across various system architectures much simpler:

In choosing the MetaSL universal shader language, mental ray 3.7+ rendering software allows artists to develop shaders that run on all popular software and hardware platforms. Artists won’t need to re-architect shaders every time there is an advancement in new generation software, GPU or CPU based rendering systems. MetaSL-based shaders adapt to fit current and future target platforms.

This version of mental ray ships with Autodesk’s 3ds Max 2010.

via CGSociety – mental ray goes with MetaSLa.