The Nobel Committee has zero credibility. Occasionally, the good folks in Oslo get it right (e.g. Archbishop Desmond Tutu, President Jimmy Carter, etc.) And sometimes, they get it wrong... dreadfully wrong.
Henry Kissinger butchered countless women and children in Cambodia before he received his "peace" prize.
Yasser Arafat murdered countless women and children in Israel before he got his "peace" prize.
And now, Barack... the Great Black Hope, has gotten his "peace" prize after bombing countless women and children in Afghanistan and Pakistan.
I'm no fan of the late Ronald Reagan, but he did preside over the end of the Cold War. He wasn't solely responsible for ending it -- after all, every US President from Harry Truman to Jimmy Carter played a role -- but he did play his part in peacefully ending a global conflict that lasted almost half a century. And he did not receive a Nobel Peace Prize.
Bill Clinton stopped the Serbs from committing genocide in the Balkans. And he did not receive a Nobel Peace Prize either.
The Nobel Committe made a political decision by awarding the peace prize to Obama. The Europeans like him for being the anti-Bush... except he's not really the anti-Bush. He's escalating the war in the Af-Pak region, he has continued to use private military contractors (read: mercenaries who are accountable to no one), and he has yet to shut down Gitmo.
Mohamed ElBaradei, another Nobel Peace Laureate, won his prize for pretty much the same reason: standing up to Bush. The only difference between ElBaradei and Obama is that the former actually did stand up to the neoconservatives in the Bush administration who wanted war with Iran. Obama, on the other hand, did absolutely nothing to stand up to Bush during his 3 years in the Senate.
But hey, as Silvio Berlusconi would say, at least Obama has a nice tan. ;)