Unfortunately, because of the way I coded it, it's not available online right now. Every time it runs it looks up a bunch of friends lists through the Twitter API, and since the limit for accessing that is so strict, I can't have the app running very often (150 lookups per hour). I need to set it up to read from a DB and update that DB slowly, but I haven't gotten around to it yet.
What's being visualized are the users that have tweeted with the hashtag for the conference: #BDSMS, and how they are connected to each other.
If I do get it running online, I'll post it here.
Interactive Twitter friendship visualizer