Bullmoose explains why Harry Reid's cheap stunt may do the Democrats more harm than good:
While the war is increasingly unpopular, the Democrats should be careful that they are positioning themselves as a party that is gullible, feckless and indecisive on national security. It may provide immense partisan satisfaction to flummox the Republicans on a procedural maneuver, but beware of the long-term impact on the party which already suffers from a perception of being weak on national security.
Peter Beinart sounds a similar alarm here.
UPDATE: Fester posts his thoughts here. I should add that I do not agree with Marshall Wittman's view that the war in Iraq was inevitable, nor that it was best to "err on the side of vigilance." I do believe that Democrats have zero credibility on foreign affairs right now and that Reid's antics won't help.