From The New York Times:
Beyond the general concern about instability is a shared concern in Sunni-ruled countries - Egypt, Jordan, Saudi Arabia and the smaller oil-rich states of the Persian Gulf - that the greatest beneficiary of the war so far has been not Iraq, but Shiite-dominated Iran. Empowering Iraq's Shiite majority, they fear, will embolden Shiites elsewhere to challenge their own ruling Sunni Muslim classes. This, in turn, could encourage a spread of Iranian influence that was held in check by Iraq when it was ruled by Sunni kings and dictators...Terrific. Just terrific...
Iraq's Shiite leaders, who have been among the most enthusiastic supporters of the election today, have steadfastly maintained that a pluralist democracy, not Iran's theocracy, is their model for government, and Iran itself has tacitly blessed their approach. Nevertheless, the war strengthened Iran's position in the region by removing its worst enemy, Saddam Hussein, and whatever new regime takes hold in Iraq is likely to have friendly ties to Tehran.
Iran has also been making a big investment of resources in the social welfare, religious and political institutions of Iraq's Shiites. "There is only one country that is really doing nation-building in Iraq, and it isn't the United States," said an Arab diplomat sardonically. "It's Iran."