The image to the left is a portion of a new visualization of the blogosphere. The full image is located here. The visualization does two things. Firstly, it clusters blogs according to a measurement of connectivity designed to show communities. These communities are defined by a certain amount of cross linking.
Secondly, these communities are then laid out according to how much interlinking goes on between them. Interlinking between communities is measured by observing any links between blogs in each community. The gray lines between clusters represent these inter-community links.
Upon examining the clusters, one can observe clear thematic groupings. These may be topical: the largest cluster is the social/political cluster; others include gadgets, the tech/web 2.0 landscape, etc. On the other hand, there are cultural and locale clusters. For example, Japanese bloggers, South East Asian bloggers, etc. Finally, there are communities that are by and large constrained by hosting systems. The blue clusters are communities within livejournal.
Note that the colouring of blogs indicates the top level domain for that blog. All blogs, for example, from typepad have the same colour. Note that a limited colour palette is used, so all blogs with the same colour are not necessarily from the same domain.
The next step in this work is to label (either by hand or automatically) the clusters.