Apple are buying a company named Topsy. Topsy have access to all tweets and hashtags EVAR (apparently) and can perform analysis to see what is being tweeted about. They provide a tool for simple comparisons.
EG Are there more tweets about Jimi Hendrix or Eric Clapton?
http://topsy.com/analytics?q1=%22Eric%20Clapton%22&q2=%22Jimi%20Hendrix%22&via=Topsy
Vai or Satch?
http://topsy.com/analytics?q1=%22Steve%20Vai%22&q2=Satriani&via=Topsy
TJ's or Tanz?
http://topsy.com/analytics?q1=TJs&q2=Tanz&via=Topsy
This is rough stuff. We don't, for example, know what they're tweeting about Jimi, just that they are.
