A while back, Christopher Hitchens endorsed Obama. Hitchens is known for his unusual political views. He fully supports preemptive invasions to over thrown dangerous regimes, such as Iraq and Iran, which many of his collegues dissagree with. This is one choice he won't need to defend as much as usual.
More recently, Obama received perhaps his most important endorsement ever. Colin Powell. He is one of the most respected public officials around today, as far as I know. Here's the video from meet the press.