Patent office has agreed of facebook's face trade mark. Facebook is a payment away from trademarking the word "face," its mean that they have agreed to grand the face trademark to facebook under certain condition. So if you use special of face from facebook trademarking, then facebook can issue some payment from you. This face usage use in some service such as “Telecommunication services, namely, providing online chat rooms and electronic bulletin boards for transmission of messages among computer users in the field of general interest and concerning social and entertainment subject matter, none primarily featuring or relating to motoring or to cars.”
The face of facebook are as on the left side of this writing.