Sociology of digital communities

Eszter Hargittai at Crooked Timber reminds us that "the study of online communities is one of the oldest topics explored by academics about the social aspects of information technology use." She links to several pertinent journals and articles, and of course most of those concentrate on virtual communities, not the interaction of virtual and real. But one article in particular [PDF] includes helpful history of what might be called mediated revolutions, from 1848 to 1968 to 1989.