Most social networks and discussion boards I know tend to be dominated by a handful of people contributing over 90% of all content. This small core group (sometimes simply one enthusiastic individual) keeps the site alive by providing input and trying to encourage everyone else to contribute. The big problem is how to foster active participation.
For example, I'm involved in a Swedish education network (Dela! - which means "share") which has gathered over 800 registered users since its inception last spring. The problem is how to create a critical mass of discussion. Most users log in and read the latest news but only a minority make regular contributions and the question is how to spread the workload of keeping the network as active as possible.
The same phenomenon appears in course discussion forums where a few students dominate the discussion unless some form of incentive is provided (eg. make at least 2 significant entries in the discussion in the coming week). Without such pressure the general rule holds; 90% are passive, 8% contribute occasionally and 2% contribute a lot. How do we spread the load?
The problem is, I suspect, that people are used to being consumers rather than producers of information. Some students are uneasy about greater participation in the classroom, preferring to simply listen to the teacher's words of wisdom. Larger meetings at work or in the community follow the same lines. Just because social media offer everyone the opportunity to contribute doesn't mean to say that everyone wants to do so. It's so much easier to listen and observe.
Of course people are contributing on a massive scale to Facebook but there's a gap between the chatty social interaction there and the ability to discuss and reflect more deeply in an educational context.
What we need to develop is a kind of participation literacy; the ability to discuss and develop arguments on line. In many ways traditional debating skills are needed but we also an awareness of the rules of engagement on the net; so-called netiquette. The ability to contribute constructively to a discussion needs to be learnt and practiced in school. Those who master this skill will succeed in tomorrow's job market. According to Seth Godin, The future of the library, this type of training could be a new role for libraries to adopt
For more on this theme have a look at Howard Rheingold's interview with researcher Mizuko Ito (see Video interview with Mizuko Ito).