Three big problems
Andrew of Anecdote identifies 3 big problems for social network analysis. It's also relevant for anyone interested in social learning and communities of practice. The three big problems to overcome are: engendering trust, the illusion of accuracy and taming the expert mindset.
That feels like an enormous challenge to me in an ambient that thrives on mesquinhas and whose raison d'être is a hierarchical top-down flow of knowledge and expertise.