Note to Howard Dean (who famously had trouble reciting military personnel numbers a few weeks back on Meet the Press): The Pentagon plans on keeping around 145,000 troops in Iraq.
This may be easier said than done. As the AP notes,
Stretched thin by other commitments around the world, the Pentagon has been hard-pressed to find ground force replacements, either American or foreign.
Here's a chart covering active military personnel from 1950-2002. If nothing else, it's a stark reminder that, despite the current activity, our society is still much less-militarized than it used to be.