Here's the answer, based on the revised definition from August 2007:
A commercial interest is considered any entity producing, marketing, re-selling, or distributing health care goods or services consumed by, or used on, patients.There's an exception to this definition: The ACCME does not consider providers of clinical service directly to patients to be commercial interests.
Compare that to the 2004 ACCME definition: "A commercial interest is any proprietary entity producing health care goods or services, with the exemption of non-profit or government organizations and non-health care related companies."
In 2004, the definition of a commercial interest only included organizations that produced health care goods or services. In 2009, that definition became much broader and included organizations that were involved in the marketing or in the re-selling or in the distribution of health care goods or services.
Why is the concept of a commercial interest so important in the world of CME? For one thing, a commercial interest can't be a CME provider. You can't be an accredited provider (or a non-accredited provider involved in joint sponsorship arrangements) and develop CME content if you're a commercial interest. The term "sponsor" or "sponsorship" is often misunderstood in the CME industry. If a pharmaceutical company provides an education grant so that a university and a medical education company can collaborate to develop a CME activity, the pharma company is not a sponsor. The university and the medical education company are considered "joint sponsors" in this educational initiative. The pharmaceutical company is considered a commercial interest by the ACCME, so it can't be involved in any part of the CME activity.
You can read more here at the ACCME website.