What is the real death toll in Iraq?

People gather at the Baquba hospital morgue next to caskets containing the bodies of six of their family members who were killed by a roadside bomb south of Baquba, Iraq. Photograph: Ali Yussef/AFP/Getty images
From the Guardian:

The Americans learned one lesson from Vietnam: don't count the civilian dead. As a result, no one knows how many Iraqis have been killed in the five years since the invasion. Estimates put the toll at between 100,000 and one million, and now a bitter war of numbers is raging.