Everyone can vote posts up or down if they like. There is a feature which statistically analyses how your votes correlate with other votes, and you can choose to see votes that the analysis predicts you will find interesting and worthwhile based on what you have liked seeing in the past.
A recommendation system is even worse. That actively encourages people to look only at the path of least resistance for them. It means less emphasis on people who argue valid points that you don't want to hear and more emphasis on groupthink.
If anything, the trend should be reversed, and people should feel freer to give their opinion without a chance of whiplash.
Has the idea I proposed (essentially the Netflix recommendation system) ever been tried before for a comment/story posting system? If not, why not go the whole hog and try it? Let's see if it works.
Ask yourself: has content recommendation ever worked? I've never seen an "If you liked X you'll like Y" work for any original content. Even for movies/books it's shady at best. Working with something as complex as comments is too tricky to make worse. How do you measure tone versus stance versus wit versus writing style? They're all elements of what I look for in comments.
The easiest solutions are the simplest ones. Complexity only serves a purpose when there's a simple cause behind the complexity. Adding algorithms when there's no need will only make things less reliable.
You could take that farther and create a "pool" of good users who vote and comment in keeping with the HN style (a pool that could, of course, grow over time) and if your voting habits correlated to them your vote began to be worth more.
Subclasses might not be such a bad idea at all actually, after all there are different coffee shops for different tastes as well. If a site could be made to automatically appear as a place that caters to your 'taste' that would be a pretty awesome development. Everybody would feel right at home.
I think the behaviour I want is exactly that required by the Netflix Prize:
http://en.wikipedia.org/wiki/Netflix_prize
although rather than rating comments 1 to 5 I think I'd probably just have three levels (don't appreciate, neutral, appreciate).
Some people are here for startup stuff. Some people for codign/programming stuff. Yet others (though probably a smaller demographic) are here for social stuff. And more.
Plus others are here for a mix.
Some way to tailor what you see would be awesome! not too much that each "genre" is different but enough that the posts or articles you want to see are at the top :D