A researcher published a torrent file containing the name of every Facebook user that hasn't specifically opted out. The list was obtained by harvesting a public directory that Facebook maintains.
This list was then used to determine the likely variations of "first initial last name", "first name last initial" and so on, which could be helpful at increasing the success of users attempting to log in to systems using brute-force tactics.
The details of how this was done are available at: http://www.skullsecurity.org/blog/?p=887
