Google Ajax search results update
I have made it a habit to check the roll-out of the new Ajax-powered search results page on google.com in Google Analytics.
December 2009: 10% (proportion of traffic from google.com to my site with the new Ajax referrer)
February 2010: 20%
September 2010: Over 50%
It looks like the most recent significant bump came on August 25, 2010.
And no, this is not the death to search term tracking. In fact, you get more data, such as exact keyword ranking.