I don't like Obama but I highly doubt he knew he was being awarded the Prize. I think he was as genuinely surprised as the rest of us. But, what can he do? Turn it down? Not really...
He knows it's bogus, we know it's bogus, it's not a big deal. All it does is prove that the Nobel committee is a joke and that they've done nothing but weaken the value of the award itself. Not really Obama's fault on this one... sorry.