Simply great post on Obama's oratory from About.com thanks to Grammar Girl in my Twitter network.  Excerpt below from Barack Obama's Secret for Stirring a Crowd:

Oh sure, this may look as easy as one, two, three, but the truth is it takes more than a flag-draped stage and a run of tricolons to turn an ordinary speech into great oratory. Also helpful is the occasional series of four--a tetracolon ("democracy, liberty, opportunity, and unyielding hope")--along with effective repetition, a bit of alliteration, and a few conventional metaphors. The insistent use of the first-person plural ("we," "us," and "our") invites identification. And the right combination of anaphora ("It's the answer") and epiphora ("Yes we can") can lift a crowd off its feet and land a speech in the history books.

But that's not all. About 2,000 years ago, Cicero taught us that what makes or breaks a speech is effective delivery, which includes the qualities of dignity and grace:

All these parts of oratory succeed according as they are delivered. Delivery . . . has the sole and supreme power in oratory; without it, a speaker of the highest mental capacity can be held in no esteem; while one of moderate abilities, with this qualification, may surpass even those of the highest talent.
(De Oratore)

So to the list of Obama's persuasive skills add standing tall, speaking forcefully, and exuding confidence.

Oh, and one last thing. Especially in troubled and uncertain times, it never hurts to extend the promise of change, the prospect of hope, and the reminder that we're all in this together.

And if you haven't yet seen this hilarious video about 20-somethings' malaise post-election, click on play immediately!