First thoughts-a great website, fantastic project.  But I think a real key point he makes is that users define how social media is used, not the developers.  This is an eerie echo of Second Life, which upon starting up (2003) had exactly the same thing happen–the users quickly defined what the platform would become, which was very different from what the developers had intended.  Again it appears that in many ways SL was a precursor to the social media phenom, at least from behavioral POV.

Great data from Miller’s group, and I think we can reference their key findings as social impacts for our project.