Thanks for mentioning Carmun. I tend to agree with your point that there will be multiple social networking/media sites that people affiliate themselves with. We are all "composite" beings and expecting us to have one social network would be like expecting us to have only one set of friends/colleagues. At Carmun, we think the key is tuning the experience to a particular purpose. Thus we aspire to be the Yin to the Yang of Facebook -- or the collaborative environment to help you manage your academic life to Facebook's collaborative environment to help you manage your social life.