I like the definition from The Social Requirements of Technical Systems, now I have what CPAN realy is. I have not yet read the whole Handbook of Research on Socio-Technical Design and Social Networking Systems but the rest seems rather dissapointing.
I recently discovered that most of his work is available on-line: Collected Papers, Downloadable Books. I recommend it to people trying to understand Open Source. He is much more 'technical' than Yochai Benkler. I've just finished reading Open Source Software and the 'Private-Collective' Innovation Model.
I am working on a paper about on-line conflict in the light of mimetic theory.