I don't know if it's related to the topic of community behavior, but it's also probably worth noting that the best political posts I've seen tend to be from bloggers who generally write about technology. Similarly, the best technology-related posts tend to be written by those who focus on politics most of the time.
Being too "in the trenches" on a topic seems to lead people into saying polarizing things, or into demeaning or dismissing those who disagree with them. The voice that's used to explain things in plain english to people who aren't subject matter experts tends to lead to more rational discussions.
Maybe we just need a "switch your topic" week.