This is a link to a Multi-National Forces-Iraq press briefing where Maj. Gen. Lynch discusses the Zawahiri leter to Zarqawi.

...

I talk about the Zawahiri letter to the point where you might be tired of me talking about it. But there is something that I have not talked about in the last several press conferences that I want to emphasize. In the letter from Zawahiri, the second in command, if you will, of al Qaeda, he told Zarqawi - he says, "Remember, Zarqawi" - he says, "Half the battle is in the battlefield of the media." Half the battle is in the battlefield of the media. The terrorists will use the media as a combat multiplier to hide their limited capabilities. And let me use an example that you're all very familiar with to highlight that point.

...
This is a link with a link to the text of the letter in both English and Arabic.

...

Among the letter's highlights are discussions indicating:

* The centrality of the war in Iraq for the global jihad.

* From al Qa'ida's point of view, the war does not end with an American departure.

* An acknowledgment of the appeal of democracy to the Iraqis.

* The strategic vision of inevitable conflict, with a tacit recognition of current political dynamics in Iraq; with a call by al-Zawahiri for political action equal to military action.

* The need to maintain popular support at least until jihadist rule has been established.

* Admission that more than half the struggle is taking place "in the battlefield of the media."

...
Elsewhere, the 80 percent figure has been used, but in either case the point is the same, we are not really engaged in half or more of the battle space.

I would point out that the Arab audience is not the only one these attacks are suppose to infleunce and probably not the most important. Part of the design is to reduce support for the war in the US. That has been the most successful aspect of the enemy's war strategy, and people who can make the case in the US are certainly important to the continued success of the operation. The enemy's goal is to change our policy even if he can not win militarily.