Yeah I'm late, but I think slowly.
1. I listened to three conservative talk shows (two local and one national) in the two days following President Obama revealing his long form birth certificate. For some fraction of the callers, birtherism had taken on justification through self-referentialism. They still refused to fully believe that the President was born in the US, but they ascribed their own continuing malice and bad faith to flaws in the President. What a monster he must be to make them act so dishonestly.
2. Folks should stop acting as if birtherism is some kind of unique phenomenon. It has become quite common for some fraction of the opposition to connect the current President to the most despicable conspiracies (often worse than birtherism.) I'm not sure what fraction of the partisans actually believe the charges they are flinging about. I suspect most might doubt that factual basis of their particular charge but believe that the charge gets at something real at the core of their hate object.
Birtherism is just as stupid as the charges that the Bush Administration conspired (actively or passively) in the 9/11 attacks or that the Bush administration blew up the New Orleans levees (or otherwise conspired to flood the majority African American neighborhoods of New Orleans.) What unites all three is that they hold beliefs about the character of the President that is illustrated by, but not dependent on the conspiracy they are peddling. The hate comes first. The 9/11 truthers believe that the Bush administration was itching for a war in order to seize oil assets. The New Orleans levee conspiracists believe that the Bush administration was infinitely and maliciously racist. The birthers believe that Obama is (in some sense) anti-American and alien. Even if the conspiracies are untrue, they are still fake but accurate.
The biggest difference between birtherism and those others is that a celebrity with more marketing savvy than integrity chose to run a fake, flash-in-the-pan presidential campaign on the issue. When it came to trutherism, Rosie O'Donnell chose to remain co-host of a mainstream program (until she left for other reasons.) And Spike Lee spread the levees conspiracy but otherwise chose to remain a good citizen of Hollywood rather than running -or pretending to run - for office.
2. Like most truthers and levee conspiracists, most birthers will vote like rational political actors in 2012. Obama denied that the Bush administration was racist in the handling of Katrina and got the support of the left (mostly.) And most who have claimed that Obama was born outside the US will end up voting for a Republican who argues that Obama is a patriotic, native born American citizen who has some misguided policy ideas.
3. I've generally been disgusted by the birther issue, but some perspective is in order. I think the issue did some harm. There are opportunity costs. The time spent arguing about this issue would have more profitably been spent talking about Ryan's entitlement plans, but that mostly wasn't going to happen anyway. The Trump-related birther coverage was probably mostly going to go to some other celebrity story (royal wedding, some star passing out in a nightclub etc.) and not on issues. Even some of the coverage in the right leaning media (like Hannity calling Trump a straight shooter - gag) would have gone to something equally ephemeral. There was probably some crowding out, but not very much. Alas. Also, do you think that the median voter of November 2012 is going to vote against Pawlenty, Daniels or Romney (or whoever) because of something Donald Trump said in April 2011?
4. Ross Douthat is right that the killing of Bin Laden has reduced the political returns on finding ways to call Obama un-American. Killing bin Laden is a net positive for Obama (though intervening events and especially the course of the economy will be more important), but if it gets Republicans to spend more time talking about issues that are relevant to people's lives, it will be good for the Republicans too. And more importantly the country.
5. The most reassuring thing yesterday was Secretary of State Clinton's comments on Afghanistan where she repeated the US commitment to preventing the reemergence of an al-Qaeda client-state in Afghanistan. This is more important than the killing of Bin Laden. The Sunni Awakening and the Petraeus counterinsurgency strategy were more important than the slaying of al-Zarqawi in defeating al-Qaeda in Iraq. Killing Bin Laden is obviously much more important (s a symbolic matter and perhaps as a matter of jihadist morale) than the killing of al-Zarqawi, but it would be a damn shame if Bin Laden were killed but Afghanistan became an al-Qaeda staging base again