http://hackerne.ws/item?id=1934605
I think the primary accelerator in the inevitable slide towards 4chan is anonymity. I've seen this in my own experience: I'm anonymous on reddit etc. but use my own real name (easily googled) when posting on hackerne.ws. And the difference is potent: on reddit I am much more of a jerk than I am on HN. I think this is fundamental nature: anonymity gives you license to release your inner jackass.
I think you should require all posters to use their real identities except with special permission.
I know the standard arguments against this: how to verify identities, valid reasons for being anonymous, etc., etc. But I don't think they're enough reason to avoid a simple measure which would keep the site much more relevant, polite, and personal.