While I signed up nearly a year ago, I just recently started using Twitter. As a marketer I find it both interesting and fascinating...as it is more transparent than most social networks are. People often write back and forth using @username when they want to send another person a message, which sometimes draws you into other conversations. And since everyone you follow is someone you know or related to someone else you know it is really easy to get pulled in. And the social pressure of being associated with everything you do (no anonymous domain registration here folks) prevents Twitter from becoming a spam filled mess. Maybe there is some way such a system could be applied to search?