Hi George!
The Beginner's Guide to SEO is an evergreen piece of content that we update on a regular basis. SEO best practices change at a rapid rate due to updates in the algorithm and shifts in the industry, so we try to update the guide every 1.5-2 years, depending on the changes the update needs to reflect. The last update was released in May of 2012 (you can read more about what we changed here), and we've got another update in the works that will commence later this year.
Thanks for referring back to the guide for your SEO basics, and happy reading!
Ashley
