I like it. I looked at the source and was gladly surprised to see the cleanliness and clarity of the markup. The design is clean and clear. The colors make text legible without being glaring on a bright monitor.
I'm not personally a fan of one aspect of the markup in particular, though. The thick border between the byline and the node content followed by the thin rule between nodes reads at first as if you've used bottom attributions. It's very easy to miss that first by-line at the top and look at what is most clearly delineated. I'm not a fan in particular of bottom attributions, either, and I almost commented about that before I noticed it wasn't the intent. If you had used bottom attribution lines, that'd be merely a minor adjustment for people reading the site. I'm afraid what you have here will lead to mistakes in replies if it is implemented. Putting the whole by-line in the divider as the current design does may not look as crisp, but it is much clearer. I think an alternative would be to use quite a bit more vertical whitespace between the list items used to contain the nodes.