Where did "Key Concepts" go?

Back when Operations Manager 2007 was released, the content team posted an online version of a Key Concepts Guide and a download version. When you look at our documentation download page for Ops Mgr 2007 R2, Key Concepts isn't listed. Where did it go?

When the product was new, we wanted to highlight Key Concepts to clarify the differences between MOM 2005 and Ops Mgr 2007. With R2, we're not really a "new" product anymore. The explanations of model-based design, service modeling, and health modeling are primarily of value to the authoring experience. So, when we reorganized the content library in the R2 release, the Key Concepts content was added to the Management Pack Authoring Guide.

P.S. The links to the original content (first paragraph) still pull up the original content, but notice that the left navigation pane fails to resolve to a table of contents. Whenever you hit TechNet content and the navigation pane goes generic, you know you've reached deprecated content.