The maps* above and below are more or less self-explanatory. Note the differences in areas of al Qaeda in Iraq activity between December 2006 and December 2007. (Click images for larger views.) The insets at lower left show the improvements within Baghdad.
What immediately stands out, right after the greatly diminished AQI presence, are the paths leading straight to the Syrian border with Iraq.
Which begs the question: What the hell are Obama and Clinton doing having their advisers play footsie with the Syrian president?
* The maps are from a presentation by Anthony Cordesman of the Center for Strategic and International Studies (CSIS), which sourced the maps from Multi National Force-Iraq (MNF-I).