UPDATE:  Don’t put too much cash on the table if you want to bet that former MTV Networks chief Judy McGrath will soon be running OWN following the announcement today that Christina Norman has been ousted from the job. Discovery COO Peter Liguori was told that he’ll be at the network as interim CEO for about a year — at least into 2012. The Oprah Winfrey and Discovery Communications joint venture won’t even begin to look for a replacement until this fall, we’re told. Winfrey and Discovery CEO David Zaslav want to wait until Oprah is done with her syndicated talk show — and give Liguori time to straighten out what everyone now acknowledges has been a mess. Winfrey and Zaslav lost confidence in Norman around the end of March. They were tired of making excuses for OWN’s ratings, which nosedived after the channel made its debut in January. They also lacked faith in the development slate Norman had put together. Winfrey suggested calling in Liguori, the former chief of Fox Broadcasting who had been associated with hits including American Idol, 24, and Glee. After Zaslav agreed, they decided to sit on the decision. They didn’t want to mar Discovery’s April 14th upfront presentation to advertisers and media.

But the timing of the announcement today, one day after McGrath said that she’s leaving her long time perch as head of Viacom’s MTV Networks, seemed too neat to be a coincidence. Insiders say that nothing’s in the works to bring Judy to OWN. But they acknowledge that Discovery’s plans could change in a heartbeat: Liguori didn’t sign a new contract to take charge of OWN. And McGrath is considered a prime candidate. She’s one of cable’s most highly regarded creative executives. She’s also a close ally of former Viacom CEO Tom Freston, a consultant at OWN who’s up there with Winfrey and Zaslav in deciding what direction the channel should take. Actually, McGrath’s close ties to Freston are one of many reasons why Viacom CEO Philippe Dauman pushed her aside. He became Viacom’s CEO in 2006 after Chairman Sumner Redstone fired Freston. Still, McGrath isn’t a shoo-in. She lives in New York, and the OWN partners want the operation to be in Los Angeles. She also may not want a job that would require her to share so much power with Winfrey and Zaslav. Some executives say it may be impossible for anyone to create order at the channel while reporting to two high-powered bosses who see OWN as the venture that could define their careers.

PREVIOUS: After a little over than two years on the job, Christina Norman is leaving as CEO of OWN: Oprah Winfrey Network. Peter Liguori, COO of Discovery Communications, who has been hands-on involved in the fledgling network, a co-venture between Discovery and Winfrey’s Harpo, will serve as interim CEO while continuing in his Discovery role. Discovery and Harpo had been quietly searching for a replacement for Norman for the past couple of months, with CBS syndication executive Terry Wood rumored for the job at one point. Then speculation heated up yesterday that Judy McGrath, who stepped down as chairman and CEO of MTV Networks, may be a prime contender. She was originally approached for the top OWN job in 2008. Word is that no decision will be made for a few months and that the new person may jointly oversee OWN with Liguori. After a solid launch in January, OWN has failed to generate strong ratings and has been trending just above its predecessor Discovery Health, something Winfrey and Discovery Communications president and CEO David Zaslav have been reportedly unhappy about.

UPDATE: Here is the release announcing the change:

Los Angeles, CA and Silver Spring, MD – Peter Liguori has been named Interim Chief Executive Officer of OWN: Oprah Winfrey Network, it was announced today by Oprah Winfrey, Chairman of OWN, and David Zaslav, President and CEO of Discovery Communications.  The appointment reflects a transition from a launch phase to a more long-term focus on business and creative strategy, development and execution following the network’s debut on January 1, 2011.

Effective immediately, Liguori steps into the role held by Christina Norman, who led the successful launch of the multi-platform joint venture.  In addition to his Chief Operating Officer (COO) responsibilities for Discovery Communications, Liguori will oversee the network as it continues building a slate of new and original content, including the October debut of Rosie O’Donnell’s new talk show ROSIE and the launch of OPRAH’S NEXT CHAPTER in early 2012.

“I want to thank Christina for her important accomplishments, incredible passion and many sacrifices in helping to launch the network,” said Winfrey.  “With the final taping of “The Oprah Winfrey Show” only a few weeks away, I will soon be able to devote my full energies to OWN. This is a natural point of transition, and I am confident that Peter, as an integral part of the launch of OWN, will be a terrific partner for me going forward.  He is one of the smartest, most creative executives in media, and I look forward to his leadership as we build our development slate and work toward the launch of OPRAH’S NEXT CHAPTER.  Over the remainder of the year, Peter and I will work together to recruit a permanent CEO for OWN’s next phase of growth.”

“Joining OWN was a great opportunity, and launching it successfully and drawing more than 67 million viewers is one of my proudest achievements,” said Norman.  “My thanks to Oprah and David for entrusting me with this brand and giving me the opportunity to launch OWN.  As I move on to my next challenge, I am confident the strong foundation we have built will position the network to achieve great things.”

“Peter is Discovery’s creative leader, and highly qualified to assume the leadership at OWN for the next phase of growth,” said Zaslav.  “Christina did a great job launching OWN with long-term support from both advertising and affiliate partners.  Peter will now ensure that OWN reaches its full creative potential with great programming that delivers on Oprah’s vision, mission and brand.”

OWN debuted on January 1, 2011, and delivered double digit primetime increases across all key demos vs. Discovery Heath a year ago for 1Q.  Strong performing series include SEASON 25: OPRAH BEHIND THE SCENES, OUR AMERICA WITH LISA LING and THE JUDDS.  Key upcoming series debuts include WHY NOT? WITH SHANIA TWAIN and FINDING SARAH, with the Duchess of York Sarah Ferguson.

Among his primary responsibilities as Discovery’s COO, Liguori oversees Discovery’s interests in its joint venture channels, The Hub, 3net and OWN, as well as providing leadership for the company’s operational organizations, including Marketing, Discovery Studios, Corporate Communications and Corporate Affairs, Business Affairs, Research, Digital Media and Commerce, and Media Technology, Production and Operations.  In addition to his operational role, he also oversees Discovery’s cross-company global Creative Council with a focus on maximizing the value of the company’s content, marketing resources and overall corporate assets.

Before joining Discovery in 2009, Liguori most recently served as president of entertainment for Fox Broadcasting Company, where he was responsible for all Fox program development and marketing.  Prior to assuming that position in 2005, Liguori was president and CEO of News Corp.’s FX Networks since 1998, overseeing business and programming operations for FX and Fox Movie Channel.  Under his leadership, over a five-year period, FX grew from an emerging network reaching 39 million homes to a top-five basic cable network reaching more than 84 million homes and recording all-time highs in ratings and revenue.