It’s the end of an era, as one of the most powerful women on the planet (Forbes noted Winfrey’s net worth at $2.7 billion) Oprah pulls the plug on her talk show — and plans to launch another – on her own channel.

“The Oprah Winfrey Show,” an iconic broadcast that grew from a local Chicago talk show into the foundation of a multibillion dollar media empire, will end its run in 2011 after 25 seasons on the air, Winfrey’s production company said Thursday night.

Winfrey, who became one of the most powerful women in entertainment from a seat on the couch of her set in Chicago’s West Loop neighborhood, plans to announce the final date for her show during a live broadcast on Friday, Harpo Productions Inc. said.

Winfrey is widely expected to start up a new talk show on OWN: The Oprah Winfrey Network, a much-delayed joint venture with Discovery Communications Inc. that is expected to debut in 2011. OWN is to replace the Discovery Health Channel and will debut in some 70 million homes.

CBS distributes The Oprah Winfrey Show, and the execs there probably have their hankies out right about now, as the show was sold in 200 markets — kiss all those licensing fees goodbye.