The purpose is to distribute the workload of rendering across multiple computers - the theory is that you can speed up the overall render process.

I've been finding it very useful for complex photo montage projects; rather than rendering directly to MPEG-2 on a single machine, I'll render to DV AVI as distributed to 3 machines, then take the resulting DV AVI and render it to MPEG-2 on a single machine; this has cut quite a bit of time off the entire process.

Not aware of any tutorials. YMMV, etc.