In a virtual kind of way the links we put at the side of our blogs is the first part of creating the "multi-authored" paper though with multiple sites (see post below). The list is called a Blogroll I gather.
I thought of this as I was honoured to be added to Laurel Papworth's Blogroll. You'll note she is included in mine. And today I've added Veritas Pravda's valiant Golf,Not Tennis. From the site it appears this is intended to be multi-authored but isn't yet. I will watch with interest.
I made reference below in discussing the relevance of individuals to group outcomes one of a general category of software that performs social network analysis. This analysis could be very easily made of blogrolls from various sites, to identify "extended communities". (A similar analysis could be made of sites referred to by links in posts). Some possibly very informative research available there.
It becomes quite difficult with some blogs that have voluminous blogrolls. Hypothetically there may be interesting studies in both the roles of certain sites (some are at the periphery, others almost act as indexes), and the evolution of blogs.
Mind, this is very similar to some work that is done on academic publishing, and identifying cross-citations to determine/identify "schools of thought" (and for that matter "vanity circles" that cross reference each other to grow their citation records).