The President's new account is as personal as anything named after an office can be — @potus, an acronym for President of the United States. But it's an account that will have tweets posted exclusively by the President, which is different than the long-running, team run, @BarackObama account. The interesting thing for all of us here, of course, isn't so much the first tweet as the first Twitter client: Twitter for iPhone.

It's not the first cultural milestone for the iPhone and it certainly won't be the last. But it's a big one. It helps highlight the profound change that's happened not only in governments but by people in government. Not so long ago, anyone in office would have been consigned have been consigned to a monstrous mobile device ill-suited for anything beyond arduous text entry and stripped down web browsing.

And now the President of the United States is tweeting from his iPhone.