“The Oprah Winfrey Show” will end in 2011 as she prepares to start a cable channel of her own. Media Decoder:

A spokeswoman for Ms. Winfrey’s production company, Harpo, confirmed Thursday evening that Ms. Winfrey would make an announcement on her show on Friday. The plans were first reported by WABC, the ABC station in New York City.

“The sun will set on the Oprah show as its 25th season draws to a close on Sept. 9, 2011,” Tim Bennett, the president of Harpo, said in a message to affiliates.

WSJ:

The move is a big blow to the syndicated television market, in which Ms. Winfrey has grown to become a juggernaut. “The Oprah Winfrey Show,” which launched in syndication in 1986, attracted 6.6. million viewers for the week ended November 8, according to Nielsen Co.

Local television stations, which use Ms. Winfrey to anchor their daytime hours, could also smart from Ms. Winfrey’s decision. Her show has been one of the few whose ad rates have held steady in the recession, according to one ad buyer.

Chicago Tribune:

Speculation has been rampant [link] that she might choose to leave daytime TV ever since it was announced in January 2008 that she and Discovery Networks planned to partner on a cable network: OWN: The Oprah Winfrey Network.

The cable network’s debut, originally set for this year, has been delayed more than once and a launch date is expected to be firmed up by the end of this year for sometime in 2010. The new channel will take the place of what is now Discovery Health, available in 70 million homes from the start.

Reuters:

Winfrey, 55, is considered a major opinion-maker in the United States and this year was No. 45 on Forbes magazine’s list of the world’s most powerful people.

She publicly promoted Barack Obama during his 2008 presidential campaign and her program became a platform this week for Republican 2008 vice presidential candidate Sarah Palin to launch her book, “Going Rogue.”

Tweet tweet:

Not only does Oprah now dominate Twitter’s trending topics across multiple terms, which is quite remarkable given the volume of New Moon noise, but Trendrr has alerted us to the fact that Oprah mentions, in just the first hour alone after the news broke, skyrocketed to more than 8,000 tweets.

Tweets per hour Trendrr graph via Mashable, “we expect this to be an ongoing trend through tomorrow’s official announcement.”

I’m not thinking this is the best time to be launching a conventional cable channel, but if anyone can do it, she can.