Here’s Michael Gordon’s take in the Times:

Adding the five brigades, at roughly 3,500 soldiers each, would bring the American contribution in Baghdad to about 33,000. Expanding the Iraqi Army in Baghdad by three more brigades would push the number of Iraqi soldiers to around 15,000. American officials say that there are an additional 3,000 American and Iraqi Special Operations forces in the Baghdad area who will be part of the effort. In addition, there are 13,000 Iraqi National Police officers and 22,000 local Iraqi police officers. That would bring the total number of American troops and Iraqi soldiers and policemen to about 86,000 in the capital.
American officials say that the pervasive use of separate ministry security forces and the use of contractors to protect government buildings also needs to be factored into the equation. There are thousands of such personnel, though specific numbers are hard to come by.
According to the military’s plan, the forces would also not be distributed evenly across the city but would instead be concentrated in specific sectors. Other American capabilities, like intelligence gathering, would also be enhanced in ways that are not readily quantifiable by the deployment of the additional brigades, military officials say.
Further, military officials said that the strategy should not be considered as purely a numbers game. American commanders are considering a number of steps that would help improve security, including limiting access to specific neighborhoods and establishing “no-drive areas” and weapons-free zones.