I know facebook tracks how users browse their site and which profiles they look at, how often and how long (from articles facebook staff were interviewed in).

I know facebook tracks how users browse their site and which profiles they look at, how often and how long (from articles facebook staff were interviewed in). I wonder if they have starting using that data to recommend friends? If someone is searching for a particular person frequently enough, or regularly visiting the public parts of their profile, they probably know each other. I'm not saying it's appropriate.