I stumbled across this article/blog post on dpreview today. I think anybody who is interested in an "intermediate" dissection of ISO and its use in day-to-day photography may find this (and its yet-to-be released part two) helpful/informative.
http://www.dpreview.com/news/0909/09092304sensitivityarticle.asp
http://www.dpreview.com/news/0909/09092304sensitivityarticle.asp