The Parallel Compositing library enables developers to write scalable 3D graphics applications. The library does sort-last compositing, and works on both clusters and SMP machines. The API aims to be the MPI of parallel compositing.
Engrane3D is a fully working LiveCD OS powered by Slackware/Slax with a personalized set of tools to set, configure clusters, tools for hosting serving, a built-in parallel 3D renderer and a nice set of compilers and libs (SDL,MPI, Mesa).
Shade is an Object-Oriented, Shader-based, Distributed Scene Graph. Designed using C++ (with optional Lua bindings), OpenGL, and MPI, Shade allows the creation of applications that work on a single machine and on a tiled display.