A few places to start if you are interested in social network analysis (SNA) and teachers:
Michigan Indiana Early Career Teacher (MIECT) Study - A three year study on the social networks of early career teachers.
Pennuel, W., Reil, M., Krause, A.E., & Frank, K.A. (2009) Analyzing teachers professional interactions in a school as social capital: A social network approach. Teachers College Record. Vol. 111 (1). pp. 124-163. - I actually have yet to read this but it's on the top of my to-do list...
New book coming out - one on the authors (Purington) was kind enough to help me a bit with my own research, so I'm paying him back the favor (that's "reciprocity" in social network lingo, LOL):
Deal, T.E., Purington, T., & Waetjen D.C. (2009) Making Sense of Social Networks in School. Thousand Oaks: Corwin Press.
-k