This looks like an interesting idea. A twist on mailing lists with a web facing interface. One thing I couldn't figure out, are all threads one-on-one? Or is it possible to have threads with many people in them?

A small technical nitpick, it seems cache headers are not set correctly for images and such right now. When you scroll up and down the homepage, the same images get re-requested again and again. Out of curiosity, why are the top items unrendered when scrolling down?