It seems like a lot of this information is pulled directly from Cal's book "Building Scalable Web Sites" (Amazon: http://www.amazon.com/Building-Scalable-Web-Sites-Applications/dp/0596102356/). If you are interested in gaining some of the spoken context behind the slides, this is a great read. It was reviewed on slashdot a while back (http://books.slashdot.org/article.pl?sid=06/07/26/1357210). If your venture is a site that is going to eventually need to scale due to high resource consumption from individual users (whether this be storage, CPU, or database requirements) I suggest you pick up a copy of this book to know how to better address this concern during design rather than in deployment!