Clavicula_Nox,
I too am an Iraq vet. I served in the Baghdad AO from 2004 to 2005 doing HUMINT at the task force level. I'm not a school trained intel guy, but I worked in that capacity due to my civilian job as an investigator.
I respectively disagree with you with your linkage of Sadr, Iran, and Zarqawi. During the Battle of Holy Week in 2004, we fought a hard fight against both the Shia and Sunni. I believe many people mistakenly thought that this was a coordinated effort between the two groups. What people fail to see is that the battle came about because of two seperate events: The first Battle of Fallujah and the arrest of one of Sadr's top leaders. Both the Shia and Sunni rose up at the same time...the Shia in reaction to the arrest and the Sunni in reaction to the seige of Fallujah. I heard alot of G2 types at division level try to make the argument that the Shia and Sunni actions were coordinated. I believe it was just coincidence. I wish I could elaborate more, but I don't want to violate OPSEC.
My other point is that Zarqawi would have never communicated with Iran or Sadr. He was a strict Wahabi who would have been completely against that. I know the old adage, "the enemy of my enemy is my friend" but it doesn't apply here. Its been my experience that Wahabi's hate Shiites more than any Westerners. Also, how would Zarqawi have met or communicated with Sadr. Its not like he could walk into Sadr city unmolested or look him up in the phone book.
I do agree with you about Zarqawi's limited involvement with AQ. AQ by its own doctrine is a decentralized organization. Zarqawi didn't really come to the Western Media's attention until he started his car bombing campaign along Airport Road (RTE Irish) in the fall of 2004. An arguement could even be made that Zarqawi was a direct challege to OBL's leadership of the "global jihad".
In summary...
Zarqawi, Iran, and Sadr working in concert...no.
Zarqawi working independantly of AQ...definitely yes.
By the way, did you work for an ODA based out of RPC?