Timothy Farrar shares some interesting thoughts on parallel rendering.
http://www.farrarfocus.com/atom/080223.htm
Timothy points out an article parallel SPU rendering from GDC08 by Mike Acton of Insomniac Games.
http://www.insomniacgames.com/tech/articles/0208/insomniac_spu_programming_gdc08.php
This article has some insight turning conventional wisdom on its head. In particular, I am struck by the section on rendering fractured glass where the first approach was to take a high level view of fracturing the glass, then shove it down the pipeline. The second approach was to design a pipeline that could handle dynamic geometry, then fit the approach to the glass to what was achievable.
Old school, that's how we approached things. I feel this philosophy is a bit lost these days; top down is so ingrained in the way we are trained to think as modern software engineers - but Insomniac's results speak for themselves.