This thread should serve as a colection of links to information of interest to ZBrush users who will be rendering in Renderman or other micropolygon renderers. Feel free to add to the list.
Writing displacement shaders in RSL by Malcom Kesson
Rendering ZBrush Displacement-Maps In External Renderers - thread from ZBC
Rendering Zbrush maps in Renderman - from ZBC
OpenSource tool to convert MR to Renderman format
Advanced pipeline lighting paper
Some truly amazing ideas and examples
Render manager tool
I probably have a huge list, but I found these in the first 30 seconds and I will contribute more later.