Stratfor - yes, I know, they have predicted 10 out of last 2 wars, including the one Iran would start with Turkmenistan in order to get to its gas reserves - has published a situation report titled Red October: Russia, Iran and Iraq. The report is behind subscription wall, but some of the quotes are below:

The course of the war in Iraq appears to be set for the next year. Of the four options we laid out a few weeks ago, the Bush administration essentially has selected a course between the first and second options -- maintaining the current mission and force level or retaining the mission but gradually reducing the force. The mission -- creating a stable, pro-American government in Baghdad that can assume the role of ensuring security -- remains intact.
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The Achilles' heel of the strategy is the fact that it includes the window of vulnerability that we discussed a few weeks ago. The strategy and mission outlined by Petraeus commits virtually all U.S. ground forces to Iraq, with Afghanistan and South Korea soaking up the rest. It leaves air and naval power available, but it does not allow the United States to deal with any other crisis that involves the significant threat of ground intervention. This has consequences.
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Iranian Foreign Minister Manouchehr Mottaki attended a meeting of the Iranian-Russian Joint Economic Commission in Moscow over the weekend. While in the Russian capital, Mottaki also met with Russian Atomic Energy Chief Sergei Kiriyenko to discuss Russian assistance in completing the Bushehr nuclear power plant. After the meeting, Mottaki said Russian officials had assured him of their commitment to complete the power plant. ... While the truth of Russian assurances is questionable -- Moscow has been mere weeks away from making Bushehr operational for the better part of the last three years, and is about as excited about a nuclear-armed Iran as is Washington -- the fact remains that Russian-Iranian cooperation continues to be substantial, and public.

Mottaki also confirmed -- and this is significant -- that Russian President Vladimir Putin would visit Tehran on Oct. 16. The occasion is a meeting of the Caspian Sea littoral nations, a group that comprises Russia, Iran, Azerbaijan, Kazakhstan and Turkmenistan. According to the Iranians, Putin agreed not only to attend the conference, but also to use the visit to confer with top Iranian leaders.

This is about the last thing the United States wanted the Russians to do -- and therefore the first thing the Russians did. ... From the Russian point of view, the Americans are tied down in an extended conflict that sucks up resources and strategic bandwidth in Washington. ... The Russians see the Americans as trying to thwart their ambitions throughout their periphery, through support for anti-Russian elements via U.S. intelligence.
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If the United States plans to stay in Iraq until the end of the Bush presidency, then the United States badly needs something from the Russians -- that they not provide arms, particularly air-defense systems, to the Syrians and especially the Iranians. The Americans need the Russians not to provide fighter aircraft, modern command-and-control systems or any of the other war-making systems that the Russians have been developing. Above all else, they want the Russians not to provide the Iranians any nuclear-linked technology.
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The Russians have no interest in seeing Iran devastated by the United States. They want Iran to do just what it is doing -- tying down U.S. forces in Iraq and providing a strategic quagmire for the Americans. And they are aware that they have technologies that would make an extended air campaign against Iran much more costly than it would be otherwise. ... without a U.S. ground force..., the Russians might be able to create a situation in which suppression of enemy air defenses ... would be costly, and in which ... battle against infrastructure ... could become a war of attrition.

The Russians would happily supply the Iranians with whatever weapons systems they could use in order to bleed the United States a bit more, as long as they are reasonably confident that those systems would not be pointed north any time soon.

The Russians are just as prepared to let the United States have a free hand against Iran and not pose any challenges while U.S. forces are tied down in Iraq. But there is a price and it will be high. ... the Russians will want the following:

In the Caucasus, they want the United States to withdraw support for Georgia and force the Georgian government to reach an accommodation with Moscow. ...

In Ukraine and Belarus, the Russians will expect an end to all U.S. support to nongovernmental organizations agitating for a pro-Western course.

In the Baltics, the Russians will expect the United States to curb anti-Russian sentiment and to explicitly limit the Baltics' role in NATO, excluding the presence of foreign troops, particularly Polish.

Regarding Serbia, they want an end to any discussion of an independent Kosovo.

The Russians also will want plans abandoned for an anti-ballistic-missile system that deploys missiles in Poland.
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This is Putin's moment and he can exploit it in one of two ways: He can reach a quiet accommodation with the Americans, and leave the Iranians hanging. Conversely, he can align with the Iranians and place the United States in a far more complex situation than it otherwise would be in. He could achieve this by supporting Syria, arming militias in Lebanon or even causing significant problems in Afghanistan, where Russia retains a degree of influence in the North.

The Russians are chess players and geopoliticians. In chess and geopolitics, the game is routine and then, suddenly, there is an opening. You seize the opening because you might never get another one. The United States is inherently more powerful than Russia, save at this particular moment. Because of a series of choices the United States has made, it is weaker in the places that matter to Russia. Russia will not be in this position in two or three years. It needs to act now.

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If the United States takes out Iran's nuclear weapons, the Russians will sympathize and arm the Iranians even more intensely.
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Or the United States can quietly give Putin the sphere of influence he wants, letting down allies in the former Soviet Union, in return for which the Russians will let the Iranians stand alone against the Americans, not give arms to Middle Eastern countries, not ship Iran weapons that will wind up with militias in Iraq. In effect, Putin is giving the United States a month to let him know what it has in mind.

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Petraeus' area of operations is Iraq. He may well have crafted a viable plan for stabilizing Iraq over the next few years. But the price to be paid for that is not in Iraq or even in Iran. It is in leaving the door wide open in other areas of the world. We believe the Russians are about to walk through one of those doors. The question in the White House, therefore, must be: How much is Iraq worth? Is it worth recreating the geopolitical foundations of the Soviet Union?