The five parts of her presentation are spread across 5 posts to her Full Circle Online Interaction Blog. The link below is to the fifth one, which includes links to all four previous parts.

The nature of a community can be defined by three dynamics: the relationship between individual and shared identity, the way boundaries form, and  the way learning flows from individuals back into the community. While Blog communities resemble forum or bulletin board based communities in the flow of learning, but differ in the way boundaries show up and the relationships between individual and shared identities. Another way to look at communities is from a network perspective, and the 6 functions people play in networks: Filters, Amplifiers, Convenors, Facilitators, Investors, and Community Builders (see article below). These functions provide a useful framework for discovering how a particular community operates. A further set of things to consider are the impact of how blogging tools are deployed, the social architecture and processes of interaction, the role of content, and scalability and lifecycle.

There are at least three main patterns of blog communities. The "One Blog/Blogger" community forms around a single blog or strong voice, who determines the primary identity of the group and holds the power to shape it through comment moderation. This a hub and spoke network, with key commenters eventually becoming their own hubs. The "Topic-Centric" blog community forms between blogs/bloggers linked by a common subject or passion. The community is loose and decentralized, with Identity and power distributed over a network of linked blogs, and with sub-communities dynamically forming and reforming.   The "Community-Centric" blog community forms within a larger platform such as a social networking site like mySpace, where the community is bounded by the platform. This type of community much more explicitly emphasizes the social community, and things such as relationships, popularity, and status within the community are tracked, and explicitly displayed in terms of number of posts, comments, and links. Power is determined by frequency of posting, and who comments on whose blog.

The Design challenges and Social Implications of these three types of communities are the following:

Blog Centric:
Since the community forms around one blogger, the interaction occurs only in the comment threads of her posts, which makes scalability of comment threads an issue, especially the difficulty in finding information within them. The hub and spoke structure of the network causes call and response between blogger and commenter to dominate over dialogue and turn-taking among the whole community.The Blog owner is the central authority, and topic focus is likely to move with the blogger not with the community, furthermore, the community would likely disappear without the blogger.

Topic Centric:
There is no central repository of conversation, and no central location to find the community. Links are made through both the content and through relationships, and also through other social content sharing tools such as flickr. The identity of a blog is shared between the identity of the blogger and the topic of the blog. The conversation and  moderation is distributed among several blogs, so dialogue happens between posts and comments, and there is lots of back channel conversation. The Rhythm of activity follows the rhythm of news related to the topic. Other methods, such as events and aggregators might need to be utilized to bring the community closer together as a self-recognizeable whole. Because the community is distributed, it is loss tolerant, and does not depend on any one blog for its existence.

Community Centric
A profile and login provide a clear identity, an entry point, and emphasizes the boundary of the community. In addition to blogging and commenting on other blogs, the community uses other tools to connect to each other, and so dialog and interactions also take place outside of the blogs, with comments  and posts  often used as feedback and affirmation of these other interactions. The focus is on ongoing interactions between members, and norms and agreements across the community are emphasized over individual control. Individual identity is formed through participation in the community.

Other Questions:
Are there differences in the role that content plays in the different forms of blog communities. Do the communities scale differently, what role does the genre or purpose of the blog communities play (ie, Journalism, Professional knowledge-sharing, Hobbyists, etc). What's the relationship between identity and control?

Nancy White's blog, Full Circle Online Interaction Blog is a good resource beyond just this one presentation, but not all of it is directly relevant to web development for interactive learning, so i chose to post just this article. Poke around a bit, though, or even subscribe, as there's loads of good stuff there.