Usage: http://ouseful.open.ac.uk/twitter/friendviz.html?q=YOUR_QUERY&typ=TYP where TYP is either q or tag, where q runs a normal Twitter search and tag runs a hashtag search.
For more information, see: OUseful.info: Using Protovis to Visualise Connections Between People Tweeting a Particular Term
Try you own search term: