well, the very first signs of an open civil war would be that the Iraqi Army/ Security Forces will either starting disbanding in large numbers, or split apart and start killing each other. Obviously the insurgents and hardliners aren't doing very well and keeping the peace, but the heart of the Iraqi Conflict is maintaining it's Police and Security forces. If the Iraqi Army doesn't dissolve then it'll just be civil strife and unrest, if the Iraqi Army dissolves it will be utter chaos between a 100 (at least) Different Warlords all striving to become the next Saddam Hussein. Welcome to Iraq: Total War.