Very cool, thanks. I've been looking for something like this. I may fork it with a Disqus integration.
I used Disqus (which I think is excellent) for another experiment I did (much worse than Stephen McDonald's work with Mezzanine/Drum!): https://github.com/hypertexthero/hir - http://rome.hypertexthero.com/
I often think about this, but at this time still prefer not using a third party for comments, especially on a site where the comments are so important.
In my case, there's another site that I frequent that has a huge Disqus community, but it is desperately in need of social bookmarking functionality. I'm considering launching an independent site to provide it.