We killed the 10th number one man in al Qaeda of Iraq? So, the U.S. had "intelligence" about a meeting that Zarqawi was having with his advisors. They were "positive" that he would be in the particular location that they bombed.
I'm willing to bet you some big money that Zarqawi was set up by either al Qaeda rivals or Iraqi's who wanted him out of the equation. It certainly wouldn't be the first time the U.S. has been used to do the bidding of the warring factions in Iraq.
While it's a step towards the goal of eliminated al Qaeda, I don't expect Zarqawi's death to materially affect the outcome of the war.
William Arkin, in his post today, sees Iraq as slowly but surely moving towards being more secure. I'm not sure what he's smoking, but I haven't seen any evidence of that. Southern Iraq, which used to be relatively peaceful, is now a mess with Shiites fighting Shiites. Didn't he see the story of the nine heads delivered to the Baghdad morgue?
Iran continues to be the big winner in the whole equation and the risks of a regional Shiite/Sunni war have significantly increased since Bush's adventure. There will be no good ending in Iraq, only a less bad ending.