Zarqawi has been killed, along with seven of his aides:

Al Qaeda's leader in Iraq, Abu Musab al-Zarqawi, was killed in an American air strike on an isolated safe house north of Baghdad at 6.15 p.m. local time on Wednesday, top United States and Iraqi officials said today.

At a joint news conference with Iraq's prime minister, Nuri Kamal al-Maliki, the top American military commander in Iraq, Gen. George W. Casey Jr., said Zarqawi's body had been positively identified by fingerprints, "facial recognition" and "known scars." He said seven of Zarqawi's associates had also been killed in the strike.

First, the rejoicing:

Laura Rozen calls it "a great victory for the forces of civilization."

Iraq the Model is unrestrained in his joy: "CONGRATULATIONS TO IRAQ, CONGRATULATIONS TO THE WHOLE WORLD ON THIS VICTORY."

AJ at AMERICAblog: "GREAT. Whatever you think about the war in Iraq, Zarqawi was a significant threat to Coalition troops and Iraqi military forces and civilians, and his death is a victory for progress and security."

Peking Duck: "I'm glad the fucker is dead. Good riddance. A shame we didn't do it years ago when we had plenty of opportunities."

Captain Ed is hyperbolic:

The elimination of Zarqawi and his henchmen will kneecap the foreign insurgency. Although the network will still exist, the loss of leadership and political connections will guarantee its rapid decline. What little command and control existed will disappear, and the funding channels that Zarqawi controlled with go with them. Cells will operate without any coordination at all, a problem already with the successes the Coalition and Iraq have achieved against the network. They will act all at once in response to this attack, but then should run out of gas quickly.

Here is the reality check:

Nickle at Daily Kos (writing before Zarqawi's death was confirmed):

With ABC news reporting that Zarqawi is dead, and a major press conference in Iraq planned for the morning, there is a good chance that the son of a bitch might be dead. Yet the United States needs to stop acting like this is a one man show.

Word is that the man was hated on the street, and a terrible leader. And we all know that much of the violence is not masterminded plots of terrorism. Instead it is the result of sectarian violence and general resistance.

Blogenlust remains skeptical:

... it's certainly a good thing, whether that changes anything on the ground in Iraq remains to be seen. The problems we're seeing in Iraq have always been much bigger than one man, and I don't think they're going to disappear overnight.
[...]
... The problems we're facing in Iraq are tied to the crippling daily violence that has less to do with anything Abu Musab al-Zarqawi has ever done and more to do with an unwillingness on our part to adequately fix the mess. In order to fix the mess, we need to do what we should have done in the first place, which is put significantly more than 150,000 troops in country. You can't create stability any other way, and certainly not by killing one terrorist (especially since the problem, now, is less about the terrorists, and more about the Iraqi infighting).

The problem is the Bush Administration was never willing to put that many troops in Iraq, and they're certainly not willing to do it now that public opinion against the war is increasing by the week. So, how do you address the obvious problem, without addressing the obvious solution? You change the source of the problem. It's not the fact that we don't have enough troops in Iraq that's causing all the violence, it's Al Qaeda in Iraq, and it's Abu Musab al-Zarqawi, and it's because they hate freedom and democracy.

In other words, from a political standpoint, it's a lot easier to blame the problems facing Iraq and our military on an outside force, preferably an enemy, rather than something we should have done or something we're unwilling/unable to do. That's where Zarqawi comes in, and it's where he's been for a few years. I don't doubt that Zarqawi is a terrorist who's killed and created violence, but I do doubt that he's had as much influence on our problems as we're often reminded.

Magpie at Pacific Views reminds us that Saddam Hussein's capture in late 2003 was supposed to kneecap the insurgency as well. As we know all too well, it didn't work out that way.

Magpie also links to a post at Strategy Page (definitely not a liberal blog), which has some interesting things to say about tensions between Zarqawi and the mainline Al Qaeda leadership:

The relationship between terrorist leader Abu Musab al Zarqawi and and the mainline al Qaeda leadership continues to deteriorate. Zarqawi's recent audio messages have not only attacked the U.S. and the Shia-dominated government in Iraq, but also Iran. He's even claiming that the U.S., Iran, and Shia in general, are in cahoots to destroy Islam. He has also called for continued attacks against Shia.

Except for his verbal attacks on the U.S. and the Iraqi government, he is almost totally distanced himself from the central leadership. Other al Qaeda leaders have been trying to down play anti-Iranian and anti-Shia rhetoric, and have been strongly discouraging attacks on civilians.

Given that Zarqawi has become a loose cannon and that his actions are handicapping Al Qaeda's efforts, it seems reasonable to expect that an accident may befall him at some point in the near future. If handled right it can be made to look like he went out in a blaze of glory fighting American troops or that he was foully murdered. Either way, al Qaeda gets rid of a problem and gains another "martyr."

Magpie wonders:

1. Did Iran have a role in Zarqawi's death? Perhaps information on his whereabouts was offered up by the Iranians as a pro quid pro for US 'understandings' about its nuclear program?
2. Was the airstrike that killed Zarqawi essentially an intervention on the side of the Shia in the Iraqi civil war? In an attempt to salvage something from Dubya's Iraq adventure, has the US become a bit player in the ongoing drama of Iraqi sectarian politics?

Either way, it's possible that Zarqawi's death may be welcomed by the Al Qaeda leadership as the elimination of what they considered a liability to the insurgency.

BBC News has an excellent analysis piece on avoiding the temptation to draw simplistic conclusions about what Zarqawi's death will lead to in Iraq and the larger war on terror:

The death of Abu Musab al-Zarqawi is obviously a major success for the new Iraqi government and the US, but it remains to be seen if this marks the beginning of the end of the insurgency.

If it significantly weakens the al-Qaeda structure in Iraq, it could open the way for easier contacts between the government and other insurgents, who are more Iraqi nationalists than Islamists seeking to set up an Islamic state not only in Iraq but across the region.

It might also lead to a lessening of tension between Sunnis and Shias, whom Zarqawi targeted.

The new government, the first constitutional one, will have to seize this opportunity if it is not to suffer the fate of its predecessor administrations, which came to office with hope and left with disappointment.

However, the death of one man does not necessarily bring a breakthrough.

One recalls the euphoria after the capture of Saddam Hussein in December 2003.

US President George W Bush declared then: "A hopeful day has arrived. All Iraqis can now come together and reject violence and build a new Iraq."

His close ally UK Prime Minister Tony Blair echoed his words: "Let his capture bring about unity, reconciliation and peace between all the people of Iraq."

It did not happen, as we have seen.

And even after Zarqawi's death, neither the al-Qaeda elements nor the nationalists will give up. Indeed, Zarqawi's removal might well bring about an explosion of revenge by his followers.

And getting the nationalists into talks and into politics is going to be a long-drawn out affair since they have their price to exact in the form of demands for an early US withdrawal.

Counterterrorism Blog has ample expert coverage on the news and its implications, with updates and tons of links to more information.

James Joyner has a comprehensive roundup of links to news, commentary, and blogger reaction.

Final words: Here is a different perspective on Zarqawi's death. Some may find it bizarre; but I for one am thankful that someone feels this way and is brave enough to say so:

"I have no sense of relief, just sadness that another human being had to die.

"As the poet John Donne said, any man's death diminishes me. It doesn't bring my son back, and this will just bring a new cycle of revenge killings."

That was Michael Berg, father of Nick Berg, who was beheaded in Iraq -- by Abu Musab al-Zarqawi.

For those who don't know it, here is the piece of writing to which Michael Berg refers:

No man is an island, entire of itself; every man is a piece of the continent, a part of the main. If a clod be washed away by the sea, Europe is the less, as well as if a promontory were, as well as if a manor of thy friend's or of thine own were: any man's death diminishes me, because I am involved in mankind, and therefore never send to know for whom the bells tolls; it tolls for thee.

This famous text, often rendered as a poem, is taken from Donne's Meditation XVII, which can be found here.