A fellow colleague of mine just pointed out this interessting article to me and I thought a small hand full of you might also be interested: http://blog.lse.epita.fr/articles/75-sstpinball.html
Published just today, so right off the press
This article deals with the reverse-engineering of the and RAM architecture of Whitestar boards (basically how data is stored and made accessible to the CPU). Very technical, but the first half should be a good read for anyone who dows not already know what the different boards do and how exactly light and switch matrices work.