I've started putting together a very simple FAQ about SP (see the What is SP? (FAQ) link on the right). I've given up trying to format the text of the FAQ nicely as the blogger editor for such pages is unbelievably useless.
One key thing that is still missing from the FAQ is a basic description of the nodedge model. I will add this next as there have been some changes since the 2008 PDF 'paper' that is linked to from my first post.