The production shader library contains a set of shaders aimed at production users of mental ray. The library contains a diverse collection of shaders, ranging from small utilities such as ray type switching and card opacity to large complex shaders such as the fast 2d motion blur shader.
In order to enable the mental ray production shader library, you can edit the
mentalrayCustomNodeClass.mel or simply type the following into the script
optionVar -intValue "MIP_SHD_EXPOSE" 1;
Restart Maya and now, in the hypershade, you should be able to see the production shaders.
For some reason the documentation for these shaders are still a bit dated. The only version I’ve been able to find is the 2007 documentation. Master Zap has an extensive blog post on all of this if you’re new to the production shaders. When browsing through the release notes of mental ray 22.214.171.124, bundled with Maya 2011, it seems some of the shaders have been updated and bugfixed. PixelCG has done a nice job recording video tutorials on each shader.