Google has released an open source browser extension to opt out of all personalized advertising from participating advertisers.

http://googlepublicpolicy.blogspot.com/2011/01/keep-your-opt-outs.html
http://www.computerworld.com/s/article/9206061/Google_jumps_into_Do_Not_Track_debate_with_Chrome_add_on?taxonomyId=84
http://tech.slashdot.org/story/11/01/24/2125204/Google-Adds-To-Mozillas-Push-For-Do-Not-Track

...whilst at the same time, Google requires AdSense publishers to have a (lack-of-)Privacy Policy that permits Google's intrusive DoubleClick tracking cookies.