The Best Analysis of the Iraq/Iran Conflict To Date

This suggests that Iran welcomed our takeout of Saddam Hussein and knew that a civil war would take place after that, leading to a potential collapse of the US military presence, Iran's proxy armies (Hezbollah, terrorist/insurgents) would re-inforce their presence.

Tigerhawk has it here.
ahh..... try this:
http://tigerhawk.blogspot.com/2006/12/what-to-do-about-regional-war.html

It's a bit lengthy and it's only an intro, here's an excerpt:

"Had the Shia maintained what appeared to be their course politically when al-Zarqawi was killed, accommodation would seem to have been possible. But, under Iranian influence, the Shia drew back from the political process in Iraq and increased their attacks against the Sunnis. Along with this shift, Tehran encouraged its ally in Lebanon, Hezbollah, to become more aggressive toward Israel, and provided military equipment and training for this effort. The conflict in July-August 2006 was the outcome, and it stunned both Israel and the world. For whatever reason, Israel was unable, for the first time since the founding of the modern state, to crush an enemy in war. This increased the confidence of Syria, another Iranian ally dominated by an Alawite government, to raise its pressure on Lebanon.

In short, Iran had three goals. First, it wanted to be the dominant power in Iraq. Second, it wanted to be the dominant power in the Persian Gulf. Finally, it wanted to reclaim for the Shia the distinction of leading the Islamist renaissance — a position that had been assumed by Sunni al Qaeda. By the fall, it was on the verge of achieving this. The key was Iraq: Iran either had to create a situation that would force the Americans’ withdrawal, thus leaving Iraq to the Iranians, or failing that, a civil war that would divide the nation, allowing Iran to dominate the new, southern Shiite entity. That would give Iran the ability to begin to dominate the Persian Gulf, and would give it revolutionary primacy in the Islamic world."