1. A computer-implemented method for detecting social networking spam, the method comprising: using a computer processor to execute method steps comprising: selecting a central member who is a user of a social networking environment; measuring degrees of association between the central member and other users of the social networking environment; defining a social networking group containing the central member and other members, where the other members are a subset of the other users of the social networking environment selected responsive to the other users' degrees of association with the central member; identifying that a new entry has been posted on a blog of the central member; analyzing the new entry in comparison to a group usage profile for the social networking group, the group usage profile indicating a pattern of publishing activity of the members of the social networking group in posting information on blogs of other members of the social networking group over a period of time; responsive to the analysis in comparison to the group usage profile indicating that the new entry deviates from the pattern of publishing activity, analyzing the new entry using a global usage profile comprising a spam usage profile to determine whether the new entry matches a spam signature representing known spam; detecting that the new entry is spam responsive to analyzing the new entry using the global usage profile; and determining a pattern of global publishing activity of users in posting information on blogs of other users in the social networking environment; wherein the global usage profile is based in part on the determined pattern of global publishing activity.