I thought his first stumble was when he tried to insult John Howard. Sounds like time to keep an official "Barack Obama Stumble, Mistake and Gaffe Tracker", so the media can refer to something.
The "joke" he made about evacuating New Orleans wasn't pretty either; I wonder if that can still be tracked down.
Regarding the John Howard comment, he should have said "John Howard and I have a difference of opinion and if I am fortunate enough to become President, hopefully, he and I can work through this." That would have been class. But he ends up insulting not only John Howard but the Australian people as well.
Same with the Dixie Chicks. When the win their award, they have to make some snide remark about all the televisions now being turned off. No class. No grace. Either winning or losing.