As Kim Roach pointed out on SitePoint, Google has been quietly filing more patents regarding personalized search. The abstract from one of them says:

"A user's prior searching and browsing activities are recorded for subsequent use. A user may examine the user's prior searching and browsing activities in a number of different ways, including indications of the user's prior activities related to advertisements. A set of search results may be modified in accordance with the user's historical activities. The user's activities may be examined to identify a set of preferred locations. The user's set of activities may be shared with one or more other users. The set of preferred locations presented to the user may be enhanced to include the preferred locations of one or more other users. A user's browsing activities may be monitored from one or more different client devices or client application. A user's browsing volume may be graphically displayed."

I can, and I'm sure you can as well, think of many legitimate reasons that someone would want their search results filtered and/or personalized. But, unlike the movie Minority Report, you should be able to opt out very easily without having to replace your eyeballs with someone elses. I don't know about the rest of you, but for me they'd have a hard time making this work in any case. I like to periodically delete all the cookies on my machine just for fun and for paranoia reasons like someone might be trying to track my searching and browsing activities. I'm certainly not going to sign in on a search engine in order to search the web. I'm also sure my google toolbar is transmitting my activities, but as page rank becomes less and less of a definitive measure of a website's clout, I just may have to uninstall that.

There are a lot of possibilities in terms of personalization, and they may very well add a lot of value for some folks. Perhaps medical technology will progress to the point where it's not such a big deal to pop in a new set of eyeballs if you want to remain anonymous.