This incidence is an example of "QDF", or "Query Deserves Freshness". When a certain competitive keyword gets temporal spikes in links, tweets, and etc, Google

This incidence is an example of "QDF", or "Query Deserves Freshness". When a certain competitive keyword gets temporal spikes in links, tweets, and etc, Google uses QDF to give immediate boosts to these keywords on SERPs where it might not otherwise have been able to assault for years. QDF is something that's supposed to hypothetically "turn off", but with the new valuation of tweets and shares, it seems increasingly likely that these social mentions are actually beginning to count (and persist) much like links. See SEOMoz's study of how a similar thing happened to them for the term "Beginner's Guide" when Smashing Magazine tweeted it out suddenly even when it had existed (and not ranked for the term) for months: http://www.seomoz.org/blog/tweets-effect-rankings-unexpected-case-study http://www.seomoz.org/blog/tweets-effect-rankings-unexpected...