Oprah Winfrey just made her official announcement Live from Chicago.

From her daily television pulpit, “The Oprah Winfrey Show,” she told her fans of her plans to end the longtime talk show in 2011. Her program was be broadcast live from Chicago at 10 a.m. Eastern, although the time of the telecast varies on individual stations.

Tim Bennett, the president of Ms. Winfrey’s production company, Harpo, said in a letter to the program’s 214 local TV stations that her comments on Friday would “mark an historic television moment that we will all be talking about for years to come.”

Ms. Winfrey plans to concentrate on the forthcoming cable channel, OWN: The Oprah Winfrey Network.

“Big Day….tune in my tweet friends,” Ms. Winfrey’s Twitter account stated Friday morning.

Even before her official announcement, the decision was “already sending shock waves through the television world,” as NBC’s “Today” show put it Friday morning. On ABC’s “Good Morning America,” the co-host Diane Sawyer labeled it the “end of an era.”

“It’s almost impossible to comprehend the show’s reach,” her G.M.A. co-host Robin Roberts said. “She’s seen in 145 countries with 42 million viewers a week in the U.S. alone.”

Oprah reportedly told the staff of her Chicago-based show about her decision late on Thursday afternoon. Then she informed her business partners at the networks and instructed Harpo employees to start calling her local stations. The stations were told in Mr. Bennett’s letter that they could report her decision on local newscasts, apparently to increase audiences for her formal announcement on Friday.

“If you think the last quarter century has been something, then ‘don’t touch that dial’ as together we plan to make history in the next 20 months … and beyond,” Mr. Bennett wrote.

Rest assured: there's more to come from Oprah......she'll just be doing it on her OWN cable network, the Oprah Winfrey Network! Next season is going to be all about ramping up to turn that on. So don't feel sorry for Oprah...O NO! Stay tuned!