Author here, all the code is available on Github if you want to play around with the visualization or have ideas to improve it: https://github.com/whichlight/reddit-network-vis.

Also, you can see a sort of meta discussion here on the /r/dataisbeautiful subreddit: http://www.reddit.com/r/dataisbeautiful/comments/1jqz3f/redd... It's kind of hilarious because people leave threads of comments to create new branches.

What I find most interesting is that you can quickly get an idea of how much conversation is in one of these discussions by the number of nodes that are colored (signifying users who have posted more than once).