Some of my research deals with communities - specifically those that are involved in developing open source products such as Linux. My first published paper proposed a model through which the social capital of developers in such communities might influence the success of open source projects. As an analogy, consider how things an entrepreneur starts might be successful based on who he is connected to in the VC network. Makes sense, I hope.
In the following years I also followed developments among other communities a list that included Facebook, Wikipedia, Orkut, Linkedin, MySpace and Twitter. I was never too impressed by MySpace or Orkut because they seemed like glorified personal webpages to me. I watched aghast as Murdoch's empire paid a huge sum for MySpace without a proper plan to monetize the value that resides in this community. My curiosity in Linkedin is driven by how well their niche positioning paid off in creating a revenue model driven by subscription and focussed services to recruiters. Further, they have also managed to generate a wealth of knowledge through their section on Q&A. Facebook ha sits pluses and minues. I see their ability to provide interfacing applications as the killer proposition; their inability to figure out an optimum way of leveraging the community connections to provide value for marketers is troubling. Twitter - seems too superficial to become anything.
My favorite is Wikipedia. It is a hybrid model with some rules and norms in place, yet it thrives on self-policing and self-organizing capabilities of organic networks. Further, the underlying purpose of providing a platform for all the world's knowledge is huge and has no ultimate end to it. That will keep Wikipedia goin on forever. Wikipedia is also closer to home - open source crowds that participate without an expectation for monetary reward. Manye have brushed aside such community models where there are no incentives to participate, only to watch in dismay as these models became successful. Now, they scramble to explain why these models work. They need to read Richard Stallman.
Networking sites need to figure out how to monetize the crowds. Where there is a clear proposition, as in Linkedin, I see a great potential. Those that lack focus and are merely meeting places for a lot of youngsters are flirting with financial doom. There will be carnage in the social networking world and only few sites will survive. I am betting on Linkedin.