I’ve already discussed the corporate directory when it comes to enriching email data. It also contains information that can help build a picture of the social network. Specifically the line manager relationship is held in a typical corporate directory. If you have imported the directory like I did then there is no more to do as the employee ID and manager ID are already there. I’ve also kept historical management structure relationships on the basis that a line management period will build a relationship that tends to persist.
Martin House pointed me to an interesting paper which contains a diagram overlaying the corporate structure (from the directory) with the social network revealed by emails, looks pretty neat, must have a go at creating one.