How do so many U.S. products end up for sale in Iran?

Iran's political turmoil has raised some intriguing business questions: How would a shift to a less anti-West regime affect U.S.-Iran trade? And how much trade does the United States already do with the scofflaw regime?

Officially, only a limited number of goods can be exported from the United States to Iran, thanks to the varying sanctions that have been in place since the hostage-taking of nearly three decades ago. Under the Bush administration's "axis of evil" doctrine, the screws were tightened even further. Except for crops such as wheat and soybeans and medical supplies such as vaccines, the United States does not send goods to Iran.

Except when it does. Intrepid investigative journalists have pounded the pavement in Tehran and told of shops stuffed with everything from Apple (AAPL) iPods to Crest toothpaste, all American-made and decidedly not "officially" permitted. Paradoxically, even as the United States has tightened its sanctions, Iran's demand for American goods—fueled by a surge in disposable income due to rising oil prices—has steadily escalated. In 2007, Iran exported $57 billion worth of oil, a figure that makes up around 85 percent of the country's total export revenues, according to the Department of Energy.

The market, in its agnostic way, has responded to Iranians' collective demand and growing buying power. The most recent figures available show that the United States shipped $96 million worth of goods to Iran during the first four months of 2009 alone. Even taking into account a poor harvest that resulted in Iran's need to import more wheat than usual, that's still a big number. In 2001, the United States sent a comparatively tiny $8.3 million worth of goods to Iran; by last year, that amount had mushroomed to $683 million.

And that's just the stuff that's officially tracked. The sheer diversity of American-made items streaming into Iran's ports is staggering. The U.S. Treasury Department tends to worry about the items that could have value in nuclear or military capabilities: weapons, high-grade computer chips, and the like. But there's a veritable flood of ordinary consumer products, from perfumes and cosmetics to sculptures and electronics, that breaches the sanction barrier on a daily basis.

Where does it all come from? Technically, an American company's brand name can pop up in Iran legally only if the company has a wholly foreign-operated subsidiary that has no day-to-day contact with its nominal parent company. If that sounds like a huge headache of red tape and potential trade violations, it is; in addition, some companies that operate in this fashion have had to contend with political fallout for associating with such an unpopular regime.