Video posted yesterday featuring yours truly and my awesome colleagues goes into why we're doing social bookmarking and tagging and avatars and so on... We spend over 30 minutes expanding on Dan Truax's theme for our org: open the sites up to the community so that people can find reliable answers faster.
They followed up with another MSDN-focused video today on the site refresh and better search. Vikas and others have been telling us how much better MSDN search is now. I think the autocomplete feature simply rocks, since we boosted the number of terms in the DB from 30,000 to millions. Details on their latest release here.