From the New York Times, an article entitled "C.I.A. Unit on bin Laden Is Understaffed, a Senior Official Tells Lawmakers":

  Three years after the Sept. 11 attacks on New York and the Pentagon, the Central Intelligence Agency has fewer experienced case officers assigned to its headquarters unit dealing with Osama bin Laden than it did at the time of the attacks, despite repeated pleas from the unit's leaders for reinforcements, a senior C.I.A. officer with extensive counterterrorism experience has told Congress.
  The bin Laden unit is stretched so thin that it relies on inexperienced officers rotated in and out every 60 to 90 days, and they leave before they know enough to be able to perform any meaningful work, according to a letter the C.I.A. officer has written to the House and Senate Intelligence Committees.