That's the line being pushed by stab-in-the-backers like Glenn Reynolds. Here's some actual analysis of the reality:
To secure just Baghdad requires, according to the Petraeus docrtine, between 150,000 to 180,000 motivated, and loyal counterinsurgents. To secure the entire Sunni Arab population outside of Baghdad requires another group of the same size, and to secure the Shi'ite Arab population outside of Baghdad means doctrinally another 400,000 loyal counterinsurgents.
The AP explains why this isn't exactly in the cards right now:
There also are signs of an unwillingness by Iraq’s leadership to commit forces to operations outside Baghdad. About 11,000 Iraqi soldiers were assigned to a U.S.-led offensive launched last month in and around Baqouba, on Baghdad’s northeastern rim. Only about 1,500 showed up, U.S. officials said...
But they're "increasingly effective"!