(hat tip to a reader) This is long overdue:
The CAB may be awarded to any Soldier, branch and military occupational specialty immaterial, performing assigned duties in an area where hostile fire pay or imminent danger pay is authorized, who is personally present and actively engaging or being engaged by the enemy, and performing satisfactorily in accordance with the prescribed rules of engagement.
Commanders at the rank of major general will have award authority the CAB.
The CAB is distinct from other combat badges, officials said. The Combat Infantryman’s Badge, or CIB, and Combat Medical Badge will remain unchanged, they said.
The Army will release an administrative message outlining exact rules and regulations for the CAB in the near future, officials said. [emphasis mine]
The final design of the badge has not been approved, and detailed rules are still forthcoming. Seems to me that it should be retroactive to 9/11/01.
UPDATE: Phil Carter has much more on this.