Nice CNET article that discusses the impossibility of personalized search. Some of the arguments are also true for personalizaton in general. I still can't believe how much money is being wasted in that area.
"Which approach is best? The best personalization is done by individuals themselves. Software or even other people can only guess--usually poorly--a person's interest. The next advances in search technology will acknowledge this limitation and make it easy for people to act on their interests of the moment--which only they can recognize. "