The idea that "a book is a place (where readers, sometimes with authors, congregate)" arose out of a series of experiments investigating what happens when the act of reading moves from the printed page to an online space designed for social interaction. as we expanded the notion of a work to include the activity in the margin, in effect we re-defined "content" to include the conversation that a text engenders. Put another way, locating a text in a dynamic network brings the social aspects of reading to the fore. (see Without Gods, Gamer Theory, Occurrence at Owl Creek Bridge and The Golden Notebook projects)
In an earlier set of notes ("A Unified Field Theory of Publishing in the Networked Era") I suggested that as discourse moves off the page onto networked screens, the roles of authors, readers, editors, publishers will shift in significant ways. For example, the author's traditional commitment to engage with a subject matter on behalf of future readers will shift to a commitment to engage with readers in the context of a subject. Successful publishers, i posited, will distinguish themselves by their ability to build and nurture vibrant communities of interest, often with authors at the center, but not necessarily always.
More thoughts here from Bob Stein and the Institute for the Future of the Book