There are lots of people on Twitter who talk visualization. Moritz Stefaner had some fun with Gephi for a view of a whole lot of those people. He calls it the Vizosphere.
This map shows 1645 twitter accounts related to the topic of information visualization. The accounts were determined as follows: For a subjective selection of "seed accounts", the twitter API was queried for followers and friends. In order to be included into the map, a user account needed to have at least 5 links (i.e. follow or being followed) to one of these a
ccounts. The size of the network nodes indicates the number of followers within this network.
Check out the high-res version in the player below.