“The question we have to ask,” Thorbjorn Jagland, the committee’s new chairman, said after the prize was announced on Friday, “is, ‘Who has done the most in the previous year to enhance peace in the world?’ And who has done more than Barack Obama?”
Based on past history, yep, they make the decision that way sometimes. At others, the award is obviously for a body of work, for example, the award to Jimmy Carter. Further down in the article, there's this, which doesn't change my mind about the award but is worth contemplating:
While some leaders and commentators around the world lauded the selection, others said Mr. Obama had not yet earned it. Should his presidency descend into a military quagmire, as Lyndon B. Johnson’s did during the Vietnam War, the 2009 award could prove an embarrassment.Several prominent Nobel observers in Oslo said the Nobel committee had put the integrity of the award at stake. But Mr. Jagland seemed to savor the risk. He said no one could deny that “the international climate” had suddenly improved, and that Mr. Obama was the main reason.