An online community is no different than the one you live in. It’s built on the same principles and it’s citizens require the same kinds of social interaction. As human beings we’re naturally social creatures, and so require some kind of interaction.
While online communities are different in the physical aspect, they connect us in ways that our physical communities can’t. This, of course, has been talked about for a long time. However, as social networks mature you see new uses of them, and the adoption by the (gulp!) mainstream. This is inevitable.
So to get the most out of a social network, you have to put a lot into it. Look at the people who are gaining the greatest value today. Are they just lurkers? No – they actively update their status, post pictures, trade pokes, and engage in conversations. They don’t hold back and treat their online persona and friends in the same way they act and interact in real life.
If there is a negative perception of social networks, it’s in the eye of the beholder. Mostly I suspect it’s because many are afraid of participating. Either because of their own perception, their unsure of how to start, or what their friends peers would say.