Finally got the free Pixar Renderman 19 non-commercial version [click here for the software] installed and working on Maya 2015 as shown below. It took a while for those of us who subscribed to the waiting list to get this software, its about 1Gb for the windows version, and installation requires a login registered with Pixar. The nin windows version is in rpm format [Fedora] which l am yet to try out.
Below animated movie Lava was rendered by Pixar using Renderman
Test renders will come later as l try this out.
Program file sizes
Renderman showing up on menu, plugin and Render window, from Maya 2015
Some screenshots below from this new development, PRMan for Blender: