I don't have a lot to say about the tragic shooting in Arizona that hasn't already been said. I've linked to a few articles on twitter about the mental illness aspect of the situation (not always favorably). I also want to point to Vaughn Bell's excellent article in Slate explaining why just saying "he was crazy" is NOT an explanation for why Loughner did what he did.
There's been a lot of talk about overheated and violent rhetoric in the past few years and whether or not that contributed in any way to this tragedy. I frankly don't think we know enough yet to say. I do still think that bringing guns to rallies, talking about "Second Amendment Remedies" and other such targeted imagery is legal but should be avoided. The wonder of our democracy is that it IS so peaceful. In the abstract, it is amazing that George W Bush could lose an election to Barack Obama and just hand over the nuclear football, because that's how it is done in this country. Despite the wide gulf between their views of the world, power is handed over peacefully. The constant use of such violent rhetoric and imagery is antithetical to the ideals this country was founded on.
That isn't to say, however, that it should be outlawed. It is possible to condemn something without outlawing it. Voltaire's (possibly apocryphal) quote really does apply here. The proposed law to outlaw putting bulleyes on your opponent is a bad idea. To be sure, putting bullseyes on your opponent is also a bad idea. But it should continue to be protected speech. There is a difference between norms and laws. I think we would all be better off if norms turned decisively against things like putting your opponent in a bullseye. I do NOT think we are better off if that sort of thing is outlawed. Free speech is important. This may not seem like much of an assault on free speech, but it is certainly an unnecessary one.