By Kevin Connolly
BBC News, Washington
When most American corporations announce the launch of a new business plan, it is done in a statement on Wall Street or at a meeting with a handful of high-powered analysts.
When the corporation in question is Oprah, Inc, the news is delivered in a slightly tearful and clearly heartfelt statement to camera.
We are being given plenty of time to prepare ourselves for the change ahead.
The last edition of the show which is syndicated to 200 markets throughout the US and 140 countries around the world will be broadcast at the end of the 2011 season.
Oprah told her audience that after prayer and careful thought "25 years seems right in my bones and right in my spirit".
It didn't feel quite like Oprah-geddon, as it was described in the blogosphere, but as you watched it you sensed that you were present at a big moment in American television history.
Such is the depth and intensity of America's relationship with Oprah that this is all being reported as the end of an era.
Viewers are reminiscing about the show where she gave every member of the audience a new car or the way she marked the programme's 20th anniversary by taking 1,000 members of staff on holiday to Hawaii.
In truth it is more about changing technologies and business models in the world of broadcasting.
Oprah became rich through keeping hold of the syndication rights to her programme as it was sold to more and more broadcast television stations.
Gestures such as giving cars away touched Oprah's audiences
The future, though, is going to belong to other ways of reaching audiences. Oprah has a new venture with Discovery, one of the big players in American broadcasting, which will be launching in 2011.
It seems reasonable to assume that she will be appearing on that new cable channel, The Oprah Winfrey Network, to ensure that it gets the best possible start on America's crowded television landscape.
That is a shift of some significance in the way business is done in American broadcasting.
If the richest woman in American broadcasting thinks it is the moment to get into cable then the industry will sit up and take note.
Audiences, though, are sitting up and taking note because Oprah has made herself a comfortable and predictable part of their lives for 25 years.
This moment of change has become an opportunity for Americans to reflect on what Oprah means, in the way that the birthday of a favourite relative gives you an opportunity to express how much you love them.
Her daunting CV - philanthropist, magazine publisher, broadcaster, literary critic, Oscar-nominated actress and producer - is only part of the story.
Nor does her extraordinary wealth explain it, although she has been described as the only black woman on earth to become a billionaire and was for several years listed as America's only black billionaire.
Her influence is so great that it amounts to a kind of power
Part of her power lies in the fact that her life story resonates with her audience, as a kind of exaggerated version of the American dream.
She was born into rural poverty in the south and survived an abusive childhood and a teenage pregnancy to build a stratospherically successful career in television and beyond.
She became a star because of the way she opened up about her problems to her audience. Something in her honesty and her sometimes painfully emotional directness struck home with a certain type of American.
She has spoken of being abused herself - and so when she deals with the issue of abuse for example, it is real in a way that other broadcasters simply cannot match.
Her audience shares her joys and sorrows. It reads the books she recommends, it empathises with her eternal struggle with her yo-yoing weight and it allows the view from her sofa to shape its view of the world.
Her influence is so great that it amounts to a kind of power. Her decision to endorse Barack Obama for the presidency long before he was favourite to win was a key moment in the campaign.
He had his own inspirational life story, of course, but in endorsing him Oprah was able to make much of hers too.
Oprah's endorsement proved a boost to the Obama presidential campaign
"There are those who say that it's not his time," she told one audience. "Think about where you'd be in your life if you'd waited when the people told you to. I wouldn't be where I am if I'd waited on the people who told me it couldn't be."
That was a moment that proved Oprah was unique. Try to imagine candidates for the most powerful job on earth seeking the endorsement of any other TV presenter.
Oprah is of course seen by African-Americans as an icon of black achievement - and so she is.
But she is a genuinely post-racial figure too - one of a very, very small number in a society which remains acutely race-conscious.
In endorsing Mr Obama Oprah was not just recognising another hard-scrabble life story which would move an audience, she was vouching for Mr Obama with a white American audience that was still getting to know him.
Much of what is being written about Oprah would almost have you believing that she is about to quit the national stage, apart from a 2010 series which she promises is going to "knock our socks off".
That really doesn't seem likely. Her new channel will consolidate her position as one of the most important entrepreneurs in American broadcasting.
But it will also give her unrivalled and unlimited opportunities to present and as a shrewd producer she will know she remains her own best asset.
This might be the end of an era for broadcast television, but you can depend on this. In every possible sense of the word, Oprah still means business.