Well, CNN didn't quite get it right. According to CNN, the survey claims that "War has wiped out about 655,000 Iraqis or more than 500 people a day since the U.S.-led invasion" where as the survey itself says "As many as 654,965 more Iraqis may have died since hostilities began in Iraq in March 2003 than would have been expected under pre-war conditions".
There is a difference between "has" and "may have".
http://www.jhsph.edu/publichealthnew...iraq_2006.html