Matt Pharr, a founding member of that Exluna/BMRT crew that Pixar sued, and also one of the authors of the seminal Physically Based Rendering book tweeted this about Pixar's announcement of the all new physically based Renderman:

"First they try to sue you into oblivion, claiming it unimaginable that you wrote a renderer yourself without having stolen from theirs, and then 12 years later they write a new renderer with your ideas at the foundation. #theironyitburns"

https://twitter.com/mattpharr/status/472392344646340608 https://twitter.com/mattpharr/status/472392393342201856