Social media will change (and is changing) the way businesses advertise online. As user generated content continues to become more and more abundant, marketing will become less obvious and more third party oriented. As businesses continue to build their social networks, marketing messages will become more personal like the question you posed to your LinkedIn group. Social media marketing leverages the power of viral marketing to get others to promote your business. Measuring the ROI is the big question. Building a social network is the start, learning how to market to it to create a buzz and viral aspect is the art. It is the frequency of contact (one on one) and not the frequency of the message that will bring in measurable results.