Iran And Iraq, Together

I'm not enough an expert to judge the significance of Iran's having brokered a cease-fire between Shia militias, one of them belonging to the Iraqi government and the other, at least still in theory, controlled by Moqtada al-Sadr. (If Iran played a role in ending the violence, did it also, by dint of its ties to certain militias, help to seed it?)

This reminds me of the propaganda victory of a few months back when Iran's Ahmadinejad was able to tour Baghdad without the enormous security blanket that accompanies much lower-ranking US officials whenever they sneak into the country.

For our politics, does Iran's influence here mean that it recognizes that it has a role to play in stabilizing Iraq? Does it panic the Saudis? Does it panic the Israelis? Does it mean that the surge has given Iran a free hand to gain credibility as the political broker while the US military did the hard work of securing the peace?