The information they gather from this could be the best thing ever for Google. They are now literally going to see how people go from site to site to site and direct ads and content to them based on that. Good move buisness wise Google.
http://code.google.com/speed/public-dns/privacy.html
In other words, your comment is anti-Google FUD.
In order to stop them from doing that their change would have to be a clear criminal violation of something. Nobody would be able to sue them, and even getting them in a clear criminal violation would be tough (in the US anyway; recall the debacle of v. Microsoft).