Potential blowback for Iran?

Recently, Rumsfeld chided Iran for providing support to Iraqi insurgents:

U.S. Defense Secretary Donald Rumsfeld said Tuesday that weapons recently confiscated in Iraq were "clearly, unambiguously from Iran" and admonished Tehran for allowing the explosives to cross the border...
"What you do know of certain knowledge is the Iranians did not stop it from coming in," he said.
Rumsfeld said the weapons create problems for the Iraqi government, coalition forces and the international community.
"And ultimately, it's a problem for Iran," he added.

Meanwhile, this report suggests that Iran may be facing the threat of Sunni insurgency, but has soft-pedalled it:

On 13 July, the Dubai-based Al-Arabiyah television station broadcast segments of a videotape that purportedly showed the execution of Shahab Mansuri, an Iranian security official. The hitherto unknown group, calling itself God's Soldiers of the Sunni Mujahedin, captured the official sometime in mid-June, releasing a video of the hostage on 20 June. In this video, the group demanded the release of its jailed members by the Iranian authorities within three weeks or receive the "hostage's head as a gift to the elected president [Mahmoud Ahmadinejad]", Al-Arabiya reported.

It would appear that disruption of the U.S.-led stabilization effort may be coming at a price for Iran.

Here's a worst case scenario. Iran is known to have biological and chemical weapons programs, has a nuclear power program, is suspected of having a nuclear weapons program, and has uranium on native soil. If a Sunni uprising overthrow were to overthrow the Shia government, it's possible that al Qaida and friends would gain ready access to WMD.