The traditional pro-war storyline to put out after incidents like these is that the terrorists are trying to make a disruption before the big report on Iraq (this time, the Petraeus Report), with the implication that we are winning but that they are going to get enough propaganda to offset it.
The implication is always that the terroorists are losing, but that they can make one last show of might in order to discourage us.
The problem with this storyline is that they have done this several times. Eventually, one has to admit that if they still have the ability to pull these things off, then pehaps they are not losing. This can't just be a lucky break or a last-ditch effort every time.
That is all.