Best case scenario: foreign Islamofascists known by the Sunnis to be involved in the Mosque bombing or some other rogue operation. They are cleaning up their own mess.
Worst case scenario: Sunni and foreign Islamofascists killed by Sadr loyalists or some other Shiite militia.
I suspect Iraqis know who is doing what without a score card. In the meantime, we can do no more than stand by and hope that reason prevails once the smoke clears.
I wouldn't necessarily consider your best case scenario outside the bounds of reason in this case and given the circumstances.
I have to agree. This was a clean, professional hit in Sunni domain. The Sunnis are much more adept at such an operation than the Shiites.