An excellent new resource from the United States Patent and Trademark Office is the subsection of their site Stopfakes.gov.
They offer some nice descriptions of patents, trade and service marks, and copyright, and about how to protect your intellectual property.
Piracy, counterfeiting and the theft of intellectual property pose a serious threat to all U.S. businesses. Industry estimates of the cost of such theft range from $250 billion to 750,000 jobs per year. Small businesses often find themselves at a particular disadvantage because they often lack the resources and expertise available to larger corporations.
While you can find more detailed materials as the US Copyright Office, and the rest of the USPTO, this site is intended as part of an actual educational campaign with free seminars offered to small business owners to help them learn more about protecting their works.
(via a comment from Alan at Small Business Reading Room)