The release of President Obama's long-form birth certificate certainly didn't silence the Birthers, but, regardless, there's room for many ridiculous conspiracy theories on the right -- not that Birtherism is a theory, it's more of a sickness of the mind -- and the killing of Osama bin Laden has produced a new one, Deatherism, with Deathers questioning the veracity of Osama's death.
(Sigh.)
Deatherism lies mainly on the right, where Obama's Republican opponents will do, say, and think anything that seems to discredit him, however insane, but it's not exclusively a right-wing phenomenon. Regardless, I doubt it will have much staying power, and certainly not nearly as much as Birtherism, largely because most of Obama's critics are criticizing him on other grounds -- a few on the left, like Michael Moore, criticizing him for acting illegally in "executing" Osama, many more on the right criticizing him for any number of ridiculous things, like being too slow to act, and/or, like David Koch, refusing to give him any credit at all.
I myself have been critical of the White House's handling of the post-killing spin, but on the basic fact of the incredibly risky, incredibly courageous action to raid Osama's hideout and, yes, kill the terrorist mastermind, Obama deserves enormous credit.