Iraq Conflict Highly Regionalized
The reality is that Baghdad is the epicenter of the conflict. It has been from almost the start of the war, the center of the struggle for power by the many groups that are involved in perpetrating violence.
For the insurgents, Baghdad represents “center stage” where any act of violence against civilians gets immediately broadcast world-wide. If the insurgents lose the power to kill civilians in Baghdad, they know they have lost. Thus, they will invest as many resources they can in ensuring that violence on Baghdad’s streets remains a staple of evening news broadcasts. When they lose the ability to project violence into Baghdad, they will have lost, and they know this.
Regionalized control of Baghdad remains an overarching goal of many militias, including Muqtada al-Sadr and his struggle to maintain control of Sadr City. Of course, much of the horrific violence seen in recent months is the result of attacks by the various sectarian groups on each other, with much of this violence necessarily focusing on Baghdad, the Crown Jewel of all the competing forces.
The fact that Baghdad plays a separate role in the ongoing conflict from the rest of Iraq, can be easily seen by simply looking at causality rates of Baghdad, compared to the rest of Iraq:

These numbers are from IraqBodyCount, which are based on media accounts. While the absolute rates are probably not accurate (there are arguments going both ways that some deaths may not be reported, and that other incidents may be over-inflated due to questionable media sources), the point made is clear.
The reality is that for much of Iraq, the conflict has not changed dramatically in character since the start of the insurgency in 2004, with the exception of the nationwide increase in violence, post the February 2006 mosque bombing. There are regions in Iraq that are as safe as any comparable region in the United States (particularly Kurdistan and some of the southern provinces).
This is not, by the way, a dismissal of the recurring tragedies in Baghdad. But it is certainly the case that the over-focus on Baghdad by the press has in any case intensified the conflict there and led to greater casualty rates than otherwise would have been there. And it is a fact that the over-focus on Baghdad has led to very unrealistic images worldwide of what life is like for the average Iraqi citizen.