It's clearly an authoritative resource. I did a backlink check on Yahoo for it and it's got over 1400 sites linking to it And a lot of them are very well known themselves. So, it's definitely worth a look.
Of course, a lot of the information on that page would be gobbledygook to the newbie webmaster. However, a lot of isn't, too! If you just applied a few of the concepts it contains you'd be making some really positive steps SEO-wise.