http://adsense.blogspot.com/2009/03/driving-monetization-with-ads-that.html Adsense is slowly rolling out behavioral based targeting to visitors using cookies to store visitors interests. So if a user looks at lots of real estate sites, everywhere he goes he will see real estate ads even on your food website. This is going to bring major changes in click through rates and CPC. What do you guys think about it? More discussions at http://www.techcrunch.com/2009/03/11/google-now-lets-you-target-ads-at-yourself/
The disadvantage of this would be we couldn't control our niche anymore. A site about car could possibly shows music ads.
i think this would lead to a disadvantage at the end, what if the computer is used by one or more people !!
And it requires a policy update, too. Not good if multiple people in the same family (but with very different interests) use the same computer. This is a step backwards.
99% users who clicks on ads in my site doesn't even know what "Google ads" are and most probably(99.99%) might not have set the behavioral targeting page of Google. So I don't think there will be any 'SPECIAL' fluctuations in my Adsense earning due this UPDATE Anyway let's not forget the remaining 1% who clicks on my ads.