According to a July 4, 2006
New York Times article:
"The realignment reflects a view that Al Qaeda is no longer as hierarchical as it once was, intelligence officials said, and a growing concern about Qaeda-inspired groups that have begun carrying out attacks independent of Mr. bin Laden and his top deputy, Ayman al-Zawahiri.
"Agency officials said that tracking Mr. bin Laden and his deputies remained a high priority, and that the decision to disband the unit was not a sign that the effort had slackened. Instead, the officials said, it reflects a belief that the agency can better deal with high-level threats by focusing on regional trends rather than on specific organizations or individuals.
"'The efforts to find Osama bin Laden are as strong as ever,' said Jennifer Millerwise Dyck, a C.I.A. spokeswoman. 'This is an agile agency, and the decision was made to ensure greater reach and focus.'" See
http://www.nytimes.com/2006/07/04/washington/04intel.html