is recommended by the creators of sintel movie
"I would really recommend using the netrender script that is now in 2.5. We decided to use our own scripts because they were already working and easier to fit into svn and file management we had in place here, switching to a very different system was a bit risky at the time we got the renderfarm. If you want something that works out of the box, netrender works great, it also has a web interface to manage things. I’ve tested it on the render nodes here and it worked, so it would definitely be good to use that on future projects."
Also luxrenderer with smallluxgpu looks pretty impressive : the future seems to be Gpu+Cpu+Network