Hold your breath...

And wait for this kind of insight on this weekend's clash in Najaf from the Post and NY Times:

Early reports indicated there were both Sunni terrorists and Shia cultist involved in the fighting. "Governor Asaad Abu Gilel as saying that the militants, who included foreign fighters, had arrived in the city disguised as pilgrims in recent days and based themselves in the orchards, which he said had been bought three or four months ago by supporters of Saddam Hussain."

An American military intelligence informed us the early indications are that the Omar Brigade, al-Qaeda in Iraq's unit designated to slaughter Shia, was involved in the fighting. Al-Qaeda in Iraq would have a vested interest in causing mass casualties of Shia during the pilgrimage to Karbala for the festival of Ashura. Over 11,000 Iraqi Army and police have been deployed to Karbala to provide security for the event.

...

Based on the reporting and information from multiple media, U.S.and Iraqi sources, the likelihood is the enemy composition consisted of a mix of the Shia Army of Heaven cult and al-Qaeda in Iraq fighters from the Omar Brigade. Cooperation between Shia and Sunni insurgent groups is not a new development in Iraq, as Muqtada al-Sadr's Mahdi Army and al_Qaeda cooperated during the Fallujah/Najaf uprisings in the spring and summer of 2004. Shia Iran has been supplying the Sunni insurgency, al-Qaeda and Ansar al-Sunnah with weapons and bomb making materials, and is currently sheltering senior al-Qaeda leaders within its borders.

This kind of activity is precisely why the surge could work.