One theme's that is being discussed a lot is the role of heated political rhetoric. While it doesn't appear that this particular event was closely related, but politicians of all stripes are re-thinking their use of langugage and metaphors of violence (I always have hated the term "war room," mostly used by civilians who have never seen anything like the hardships endured by those who serve in the military). That's a good thing regardless.
So far, the best thing I've seen is Walter Shapiro's take. He notes the trend towards less accessibility of people to their leaders, and wonders who quickly the weekend's events will accelerate this trend, and interestingly how more security would affect the mindset of Members of Congress:
Equally troubling will be the psychological effects on House members themselves as Congress gives way to the inevitable security mania. Although there is no way of proving it, I have long nurtured the belief that living inside a protective bubble exaggerates the self-importance of public officials. If everyone must be screened and frisked before being allowed to see a freshman congressman, it is easy to imagine how this legislator might soon believe that he is entitled to perks worthy of the court of Louis XIV.