Today in Iraq

Seems to me that absolutely no one is really sure what's going on in Basra right now, although it does appear that the Mahdi Army is holding its own against the Maliki/Badr forces (or, if you prefer, the Dawa/ISCI alliance). At such times, it's best to go with those who keep closest touch with the region...
Here's Juan Cole's summary of the news from Iraq.
And here's Marc Lynch's summary of the theories about why the Maliki government is moving against the Sadrists now.

Again, it's important to set the stakes. This is not just about Basra. It's about who will ultimately control Iraq, a Shi'ite majority country that will be governed by Shi'ites. This is a contest between the two main Shi'ite family dynasties, the Sadrs and the Hakims. It was precipitated by the announcement of local elections in October, elections that are likely to see significant Sadr gains.

Remarkably, the Hakims are favored by both Iran and the United States. The Sadrists are a populist, nationalist movement, with a great deal of support among poorer, urban Shi'ites, especially in Baghdad; Iran has given the Sadrists some support--on the "enemy of my enemy" theory--but the Sadrist movement ultimately is as opposed to Iranian encroachment as it is to the U.S. occupation.

Obviously, a complicated situation. And perhaps a crucial one. I'll try to keep close track as it unfolds.