Are rouge elements of the Iranian military supplying Iraqis with weapons? Probably. But if the Iranian government was involved don't you think they might manufacture such weapons without Iranian markings? I would have to guess they would.
So, what we know for sure is that some Iranian weapons are getting into Iraq. But the Iranians surely wouldn't be selling them directly to the Sunnis who are overwhelmingly responsible for the vast majority of American casualties. Iranian weapons are more likely going to the Shia who are, in turn, stockpiling them or even selling them to their enemies to use on American forces. Unless we go after al-Sadr, why would most Shia even bother to attack Americans. We're sort of doing their dirty work for them when we fight the Sunni led insurgency.
Look, anytime you have a clusterfuck such as Iraq, weapons are going to flow in from all over the globe. I've even heard that the Sunnis have purchased Strella manpads from the Romanian black market and that these are indirectly responsible for the rash of lost helicopters lately. (Flying lower to reduce the threat of surface-to-air missiles raises the threat of being brought down by heavy machine guns. The only way to avoid both is to fly above 12,000 ft where the choppers are less effective.)
Also, over the weekend I heard that the military would produce documents to back up their claims that the Iranian government was involved. None of those documents showed up in the sixteen page power point presentation given to the press, which is available here. Now it is true that if they were included I wouldn't have been able to read them, but someone could and therefore be able to question the legitimacy of those documents.
Update: The Chairman of the Joint Chiefs, General Peter Pace, had the follwing to say today in Australia. From VOA:
"We know that the explosively formed projectiles are manufactured in Iran. What I would not say is that the Iranian government, per se (specifically), knows about this," [Pace} said. "It is clear that Iranians are involved, and it's clear that materials from Iran are involved, but I would not say by what I know that the Iranian government clearly knows or is complicit."
Not quite a ringing endorsement, is it?