great article on the gold rush that is going on around online social networks. Everyone agrees that being able to tap into the power of common interests is huge. As the article points out our friends are "our trusted sources".
What is easy to forget is the business model around harnessing this power is still undefined. Even the largest online communities like FaceBook and Twitter have yet to define how they will turn social connections into advertising dollars. That being said there certainly have been some promising studies correlating our social circles with behavior. This article has no great theories on the right answer but does give a good sense of the different efforts that are happening.
Personally I find the current "wild west" of social media fasinating. Sure I enjoy getting updates on what my family, friends, coworkers, etc. are up to but that is not what keeps me engaged. The potential of mining our personal choices and being able to customize how we live, work, shop, etc. is vast. Imagine knowing that the next book you buy or DVD you rent is the result of carefully calculations which consider multiple factors about you. Chances are the quality of that experience will be higher than the "hunt and peck" methods we use today.