Facebook is emerging as the current dominant player in the social networking arena, so I'll use Facebook as the example in the remainder of the article. In a few years, another player may emerge and Twitter is making great inroads into the social arena. The techniques will change, but the principles will remain - plan your own implementations to allow you to switch to another method when it arises.
One of the key things to remember about the Internet - its power is not in connecting computers, it's in connecting people.
The primary component for Facebook is a profile. An individual creates an account and begins to build their profile and their network. While profiles are intended for individuals, the equivalent, or at least a close approximation, for an organization is a Facebook page. For individuals gathering around a common interest, there are Facebook groups. It is important to understand the differences and nuances of each to make the most of your social networking efforts. I'll leave you to discover the various components of Facebook (and other social networking sites) and focus on their place in your online presence.
First of all, social networking sites, while they do provide a lot of features for very little investment, are not suitable as a substitute for your own domain and site. Why? Well, there are a number of reasons - not the least of which, most of the sites require users to sign up and create a profile even to just view the content there. While the process is usually quite simple and the users bear no cost, it is a barrier to entry. It also keeps your content from being indexed by the search engines.
Secondly, the loose structure of social networks does not allow you to present information in any kind of orderly fashion. Information you may want to be sure your visitors can easily find may get overwhelmed by the activity of the community.
Another reason a social network site cannot take the place of your own site is the sustainability of your content - if all your content is on a site controlled by someone else, what happens when that site is no longer available, or is replaced by something even better?
Despite these shortcomings, social networks do have some saving graces - the sheer number of people already on them is a compelling reason to participate. The casual atmosphere also encourages discussions that might not happen on your site. Face it - trying to duplicate the success of a social network site on your own will be no small feat, especially when there are big players that already know more than you do about creating success in this arena. Ideally, if you can integrate the content you post on your site into a social network page or profile, you can leverage the power of the social site and still have the benefits of a site you control.