Updated 11:33 a.m. PDT with new @Oprah follower statistics.
The official answer is in regarding Twitter Chief Executive Evan Williams' teasing tweet Thursday about Friday being a "very big day": @Oprah.
Oprah issued her first tweet around 7:10 a.m. PDT Friday--the same day Williams and Twitter's top celebrity, Ashton Kutcher, will join her on the show.
"HI TWITTERS . THANK YOU FOR A WARM WELCOME. FEELING REALLY 21st CENTURY," she said, in etiquette-trampling all-caps.
It's easy to roll your eyes at the Twitter hype. The 30-person company still doesn't have a business model. A Google advertising partnership or an acquisition would have been more exciting news for the tech crowd. But here's why the Oprah moment shouldn't be dismissed lightly.
Within about 15 minutes her first tweet, Oprah had more than 76,000 followers, with a hundred more arriving by the minute. Four hours later, she had more than 125,000.
She embodies an element of mainstream America and has sway over a vast audience. An Oprah endorsement makes it a lot easier for a start-up to legitimately argue it's broken out of its tech niche, or at least is breaking out of it.
Vying with Oprah for Twitter celebrity du jour status is Ashton Kutcher, aka @aplusk, who on late Thursday became the first Twitter user to attract 1 million followers. He gave Oprah a hello tweet Friday morning, which given the breadth of his following, likely will accelerate the rate at which people sign up to follow TV's diva.