Updated below: In a curious deal, Oprah Winfrey and Discovery (NSDQ: DISAB) Communications (NSDQ: DISCA) have formed a new 50:50 joint venture called “OWN: The Oprah Winfrey Network.” The new multiplatform media venture, the first time Oprah’s company has developed a full TV network, will be “designed to entertain, inform and inspire people to live their best lives”, the companies said. OWN will debut in 2009 in more than 70 million homes, on what is currently the Discovery Health Channel.  The venture will also include Oprah.com.

Winfrey will serve as Chairman of OWN and the venture will be 50:50 owned by Discovery and Harpo, Oprah’s company. This is a cashless transaction and OWN will be an independent company. Discovery will contribute to the venture the Discovery Health Channel as well as handle distribution and other operations. Both organizations will contribute ad sales services to the venture. The search for a CEO for the new venture is going on. More details in the release.

Updated: MCN, reporting on the joint conference call after the announcement: Unlike with Oxygen Media—where Winfrey served as a board member and which NBCUl recently bought—Winfrey said she will have control over every piece of programming that ends up on the new network. She was disappointed that Oxygen “did not reflect my voice,” but she declined to name specifics.

Update 2: If OWN takes off, and particularly if Winfrey moves her talk show to the new network in a few years, the TV businesses of several major media companies could be hurt. CBS (NYSE: CBS) owns the syndication concern that sells the Oprah show to stations across the country. A successful OWN could also interfere with the efforts of NBCU to establish a female-oriented franchise, this WSJ story says.