I recently made some improvements in my graph display code for a client and have used it to create a new graph showing the vocabulary relationships between many celebrities on Twitter. The post More Twitter Account Graphs explains a little about what the similarity is based on.
The central people in this set appear to be RyanSeacrest, PaulaAbdul, and TheEllenShow. The similarity score between Ryan and Paula is 19.8% and the top words connecting them together are: 'radio', 'game', 'guys', 'adam', 'movie', 'coast', 'studio', and their respective Twitter IDs.
Another interesting grouping is BarackObama, schwarzenegger, and timoreilly. The similarity score between Obama and Schwarzenegger is 16.7% with the top connecting words being 'health' , 'care', 'video', 'president', 'address', 'vote', and 'event'.
I included jtimberlake in the analysis as well but he was removed from the final graph because he wasn't connected strongly enough with anybody else. His closest match was only 4.5% and was with Oprah.