I came across a story in Le Monde today that is reporting that U.S. and Iraqi troops are building a wall around the Baghdad suburb of Dora, which is of mixed Sunni and Shia population. Here's the link for the
Le Monde article (the story is in French).
This area has evidently been the target of Shia death squads many times over the last few months, and the objective of the wall is to protect the Sunni inhabitants who remain in the suburb.
I could barely find references to this story reported in the American media today--the only other media outlets that came up in a Google search were foreign websites such as Kurdish Aspect and People's Daily online (China).
The Reuters story on this subject was posted on the ABC News website but not so far on any American newspaper website.
It looks like the U.S. Army is starting to partition Iraq all on its own.