"Google is handling SSL search queries on
https://www.google.com/ in a manner significantly different than the standard, expected SSL end-to-end behavior — specifically relating to referer query data. These changes give the potential appearance of favoring sites that buy ads from Google. Regardless of the actual intentions, I do not believe that this appearance is in the best interests of Google in the long run."
http://lauren.vortex.com/archive/000906.html