tedster - 2:14 am on Apr 28, 2011 (gmt 0)

Whitey, that's a pretty theoretical/abstract question, but I'll make a couple comments.

I don't think Google has a direct measure of usability in their algorithm, only what they can infer from user data as to how pleasing or not the page is for the visitor. I'm sure that taxonomies of all kinds (query intention, document classifier, user type, etc) play into ranking, but it's more like the framework that Panda operates within - again not something directly part of Panda.