A posting on Search Engine Land blog starts out with the following:
"On Friday afternoon, [Dec. 4, 2009], Google made the biggest change that has ever happened in search engines, and the world largely yawned. Maybe Google timed its announcement that it was personalizing everyone’s search results just right, so few would notice. Maybe no one really understood how significant the change was. Whatever the reason, it was a huge development and deserves much more attention than it has received so far."