When al Qaeda leader Abu Musab al Zarqawi was killed in Iraq on June 7th, some were surprised at the rapidity with which American raids began against Zarqawi associates, safe houses, etc. (reportedly 36 within a day or so and over 450 within a week). Over a hundred terrorists were killed during those raids, and over 700 arrested. Much additional material (documents, computers, cell phones) has been captured. There were so many new targets, that about a third of the raids were carried out by Iraqi forces alone. This suggests that there's something more going on than a careful perusal of the documents and laptops captured with him. It takes time to sift the docs and bytes, and time to coordinate that many raids. Even by American standards, that's very quick response to recently captured information, unless they already knew enough so that they could have the ops ready to go as soon as Zarqawi was popped.
This suggests a traitor or traitors in or close to Zawqawi's inner circle. It also suggests that the al Qaeda leadership probably did not decide to get rid of Zawqawi, as bin Laden and his close confidants would certainly not have wanted the entire network rolled up.
In any case, bumping off Zarqawi has probably seriously destabilized al Qaeda in Iraq. The spike in al Qaeda attacks that has occurred since Zarqawi's death is less likely the result of coordinated effort than a spasmodic response by his angry followers. The newly "appointed" leader is a total unknown, and certainly hasn't had time to give very many orders. He may not even be actually in charge, but rather be a front man for a junta that's supposed to keep its head 'way down. Even if the new leadership is as able as Zarqawi, it will probably take a long time for al Qaeda to recover.