Diane Sawyer Announces Last Week on 'Good Morning America'

Dec. 7, 2009— -- After 10 years on "Good Morning America," Diane Sawyer announced this morning that will step down as co-anchor this week.

"I've calculated -- 2,881 shows," Sawyer said. "Roughly."

Sawyer, 63, will take over the "World News" anchor chair, starting Dec. 21, succeeding Charles Gibson, who will retire Dec. 18.

"I hope you celebrate with us this week, laugh with us this week," Sawyer said.

"It is so difficult," co-anchor Robin Roberts said today, calling Sawyer "my Thelma. Thank you, we are going to do all things just like you this week."

Fox News host Bill O'Reilly commented on Sawyer's departure today during a "GMA" appearance, telling her that "just for getting up -- you guys get a B+."

After Sawyer's on-air announcement today, her fellow "Good Morning America" anchors promised to highlight some of her greatest hits in the coming week, including her 2006 interview from North Korea in which North Korean Gen. Ri Chan Bok warned that war was inevitable.

"It is amazing, I think to all of us, what we've been able to see you do on this show," co-anchor Chris Cuomo told Sawyer today. "It makes us all proud."

But some of Sawyer's on-camera moments drew some gentle ribbing from her colleagues.

"This is not a perfect person, Diane Sawyer," Cuomo joked, introducing a video clip of Sawyer behind the wheel of a car, taking red lights as "suggestions. She has her flaws – some of them, dangerous flaws."