This refers to an AP story that is considered the "flash point" that led to more than 200 shiites killed in retaliation for the sunni deaths (set on fire) discussed in the piece. From Editor & Publisher:
Charges that The Associated Press had been duped into running a false story on six Iraqis who were allegedly set on fire two weeks ago -- and had used as a source a supposedly fictional Iraqi police captain -- have continued to emerge from conservative bloggers and pundits, despite AP denials and its further reporting on the incident.
The U.S. military has questioned the story and some Iraqi officials more recently asserted that the police captain did not exist.
On Friday, Kathleen Carroll, executive editor and senior vice president of The Associated Press, issued another lengthy statement on the matter. She strongly defended the AP's account and sourcing and denounced criticism of its Iraqi correspondents.
"Questioning their integrity and work ethic is simply offensive," she wrote. "It's awfully easy to take pot shots from the safety of a computer keyboard thousands of miles from the chaos of Baghdad."