If the web is a sea, social networks are air

I'm a great believer in the value of online community-building, and in many ways it's encouraging to see that traditional media are learning from online social networks.

But the more I watch the evolution of social networks on the Web, the more a couple of things seem clear:

1. No one wants to be part of more than a few online social networks.

2. Increasingly, social networks are becoming separate from Web sites - or, put another way, social networks can have an impact on your experience on multiple sites beyond the social-networking site itself (such as Facebook or MySpace).

Earlier this year, Forrester Research analyst Charlene Li made a public presentation (and blog post) arguing that in the future, social networks would be "like air." At the time, I had some trouble imagining what that would actually mean. But now I'm getting a clearer picture.

Rich Gordon is Associate Professor and Director of Digital Technology in Education at Medill School of Journalism at Northwestern University.