Oath or no, as of right now Obama is President of the United States.
Watching his face is fascinating. I suspect that, deep down, he's a bit freaked out. I can't imagine I wouldn't be.
Edit: he just took the oath. And messed up the words a bit. Yeah, he's freaked out.
But, freaked out or no, it's done. Defying all expectations, predictions, and conventional wisdom, Barack Hussein Obama is now the President of the United States.