He certainly delivered it confidently. Whoever wrote it, this is President Obama's inauguration speech.
Oscar Wilde said something to the effect that the best, sincerest response to a fine piece of writing is the attempt to write one of your own, and as I listened I couldn't help wondering what I would have said had I been on that podium. If he can pull the American nation together, that will be a great start.
But for the irreverent (or habitually drunk and cynical), here is a cheeky cod-Obama-speech generator.