Roger L. Simon has more material on Iran's involvment in the current unrest in Iraq. I have earlier noted that Moqtada al-Sadr is Iran's man, and Iran's besieged Mullahs are of course rather desperate to avoid an American democratic success story on its doorstep.
Al-Sadr has praised both Hamas and, more importantly the Iran-sponsored Lebanese Hezbollah. There are indeed a lot of connections between the the cleric mobster and Hezbollah.