I’ve started a FAQ about issues related to using OpenGL in multithreaded programs. I felt this is useful to address some of the common questions, especially now that more and more people have multicore and multi-GPU machines.
It does not cover clusters so far in order to keep it simple and not to (Equalizer-)specific. I might add a cluster section later, though.
Comments are welcome. I hope to grow this FAQ into a valuable resource for everybody doing OpenGL programming.