Comment left at The Long War Journal
I don't think the doom and gloomers are very good analysts. This was not an attack on Shia, or Sunni, or Kurd, but a direct attack on the unified State of Iraq. I would say chances are pretty good in a blast this big that all three segments of Iraqi society were represented. If you want to re-kindle the civil war, I don't think this is the way to go about it.
I don't think the attack delegitimizes the state in the least. It does, however, serve to delegitimize the insurgency and provides for a propaganda bonanza for the state to demonise whoever they want to blame.