It doesn't appear we're selling the mullahs anything they could use to build the bomb, but by selling this stuff to Iran, we are alleviating some of the bite of the sanctions - sanctions that are already weak:

At the behest of a host of companies - from Kraft Food and Pepsi to some of the nation's largest banks - a little-known office of the Treasury Department has granted nearly 10,000 licenses for deals involving countries that have been cast into economic purgatory, beyond the reach of American business.

Most of the licenses were approved under a decade-old law mandating that agricultural and medical humanitarian aid be exempted from sanctions. But the law, pushed by the farm lobby and other industry groups, was written so broadly that allowable humanitarian aid has included cigarettes, Wrigley's gum, Louisiana hot sauce, weight-loss remedies, body-building supplements and sports rehabilitation equipment sold to the institute that trains Iran's Olympic athletes.

Hundreds of other licenses were approved because they passed a litmus test: They were deemed to serve American foreign policy goals. And many clearly do, among them deals to provide famine relief in North Korea or to improve Internet connections - and nurture democracy - in Iran. But the examination also found cases in which the foreign-policy benefits were considerably less clear.

And we are weakening the sanctions directly as well:

In one instance, an American company was permitted to bid on a pipeline job that would have helped Iran sell natural gas to Europe, even though the United States opposes such projects. Several other American businesses were permitted to deal with foreign companies believed to be involved in terrorism or weapons proliferation. In one such case, involving equipment bought by a medical waste disposal plant in Hawaii, the government was preparing to deny the license until an influential politician intervened. 

One would think we could do a better job policing these exceptions. The problem is that the sanctions aren't very effective and a lot of businesses see a market to be tapped, not a regime to be brought down. And let's not forget the State Department and their eagerness to make policy - especially when they disagree with the policy in place already.