Laurie Lock Lee from Optimice has published the results of a social network analysis (SNA) study of the Wikipatterns community (pdf). Laurie used SNA to examine the value of participation, health and value of new relationships of this particular community, using a combination of a survey and "wiki mining" to gather data.
A couple of interesting results in relation to the value a wiki brings:
"Looking at the percentage differentials, we can see that those that took on the more active roles of commenting, collaborating, editing and to a lesser extent, exploring, were associated with gaining more value from their participation. In other words one could assume that those more active participants also gained more value from being members."
"of the 22 new relationships developed through meeting in Wikipatterns.com, the majority have been rated as ‘very important’ by the respondents. This is an extremely positive result for the community in its ability to broker highly valued new relationships through participation in the wiki."
BTW I'm not entirely convinced we need a new term like wiki mining to describe the gathering of relationship data from a wiki, but its certainly worth recognising that a wiki does offer a particularly rich environment for an SNA study to draw information about different interactions.