Mathemagenic

Nancy White has a great series on blog communities. Too much to summarise, so you have to check for yourself (titles of 2-5 are mine, but based on the content):

• Part 1: Framing the Issue
• Part 2. Blog-centric blog communities
• Part 3. Topic-centric blog communities 
• Part 4. Community-centric blog communities
• Part 5. Implications and other questions 

A few thoughts:

I'd also think on platform-centric communities (e.g. "LiveJournal community", although I wouldn't define it as a community and would talk about LJ subcommunities). Those have many elements of community-centric blog communities, but do not necessary have "other" tools or share a common focus. They may emerge out of coincidence of sharing same space (similar to the communities that could emerge from people living in the same neighbourhood) since making cross-platform connections are likely to be more difficult than connecting inside the platform (and some platforms actually lock people inside with no RSS, obligatory registration and other tricks).

Something else - what happens when a weblog belongs to multiple (type of) communities at the same time? During the meeting in London where Nancy presented those ideas and I commented on that, someone suggested that my blog is a center of blog-centric community. I don't believe so, but let's imagine it's true. My weblog is also part of several topic-centric communities that do not necessarily overlap (e.g. KM community and internet/weblog research community).

Dina touches another side of it:

Reading the whole series, Nancy raises many issues which I struggle with.  I think some of us straddle all three types of blogging -- I am a blog-centric blogger with Conversations with Dina, a topic-centric blogger with a loosely-knit communities around social media, ethnography, qualitative research; and have been and am a community-centric blogger with Worldchanging (GULP - no posts there for ages from me) and all the Help blogs.  Would be interesting to see how my behaviour and interactions vary depending on where or what I am blogging.