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RenderMan is the software package Pixar built for rendering its own computer animation, and has been in use for computer effects going back to Star Trek II: The Wrath of Khan through today, noted as being used on The Lord of the Rings and Harry Potter films as well.
This new RenderMan release, version 19, is “scheduled in the timeframe of SIGGRAPH 2014,” which takes place in August. It will be compatible with Mac OS 10.7/10.8, and Windows 8, 7, and Vista. There is also Linux compatibility mentioned, and compatibility with Autodesk Maya versions 2013, 2013.5, 2014, and 2015.
If you're interested, you can register to find out when the non-commercial licenses become available.