A strong presence in social media is about far more than marketing. Some companies have really captured the idea of creating a community and leveraging the subsequent connection to their customers to energize, inform, and entertain them instead of selling to them all the time. In other examples, you will see an association or networking group become a place for learning and development that supports different business ideas, their growth, and establishing a network.
People are social animals. They are motivated to make connections, share stories, and to share their time and lives with one another. A company that is able to tap into this sense of togetherness through their business efforts and strategic plan, even when not directly related to the business, will connect to their community in a meaningful way. (It could come through sponsoring a school, a sports team, a charity, or other worthwhile endeavors.) Social networking is social, and so the more connections there are, the more you reflect the social nature of social media.