It is an interesting comment on the state of commenting. Gardening the comments section is a lot of work and not something people want to spend their time on (the Blekko blog would get hundreds of spam comment attempts every day!).

That makes me wonder if there is also an opportunity for a 'meta comment' section which pulls comments from web sites like HN, Reddit, or Slashdot and puts them below the blog / article that they are related to. You could set an arbitrary vote level cutoff limit.