I'm a huge supporter of Obama, but this prize was poorly chosen. Nobel prizes aren't awarded on who you are, but what you've done. And winning an American election on whatever grounds isn't enough for a Nobel Prize.
One speech engaged Iran and may have affected that election. Not enough effect yet. He's promised to close Guantanamo. But he hasn't done it yet. No prize yet. He's brought Russia back on board re Iran. Not enough for a Nobel. China is on board re Korea, but North Korea did that to themselves. No prize. Obama has set stuff in motion that could be worth a Nobel two or three years from now. But not yet.
He was given this prize because he isn't Bush. If I was on the prize committee, I might well have made the same decision. But it's still a bad decision.