This a very good article on opensource.org:
This article helped me in the past to explain to my manager the difference between a project, a product, a community user and a customer. And of course, there is some insight about their relationship, and common mistakes when people don't understand community management in a technological environment.
While this article is related to open source, there is a lot to learn about relationship between a company and its community in general. And the most important: your community users are not always your customers.