This site links to several visualizations created by Bruce Herr, Todd Holloway, and Katy Borner at the Cyberinfrastructure for Network Science Center. See Todd's blog post for some initial information. More information to come.
This is an updated visualization using an English Wikipedia dump from Jan. 3rd, 2008. In addition to a new layout, it adds some interactivity, like a bounding box search interface and multiple views. Note these features are alpha quality and will not work on certain platforms/browsers (it seems to work better in firefox).