This is the kind of the thing where if Republicans do it, people are ECSTATIC. (e.g. Saddam Hussein). If Obama does it, people go... hmm, whatever, lets find a way to criticize him for telling us this, because we don't like Obama. It's because the "we want revenge" people are mostly Republicans (or against Obama anyway), and they will not like Obama no matter what he does. They can take a piece of news that would normally make them really happy, and find a way to criticise it terribly if Obama's name is attached to it. There's also the fact that Republicans are brilliant at PR and Democrats are not. I am just speculating though, it will be interesting to see the general reaction.
Having said that, my opinion is that this is objectively meaningless. Osama was just like 'Goldstein' in 1984. Despite what I've written above, I think this will help Obama's popularity, and it will help diffuse some of the stupid shit Republicans were flinging at him (though, as above, I don't think anyone who was previously convinced that Obama was a Muslim terrorist will be voting for him now that he has removed Osama, and a lot of people who would normally love this kind of thing will hypocritically not be impressed or even go out of their way to find fault with it).
