Here is a quote from “The New Influencers” by Paul Gillin that I feel describes the benefit of Social Media Marketing. It’s a bit long, so I hope you don’t mind.

“Social media offers marketers a chance to … engage with their customers in a whole new way. The new discipline is coming to be know as ‘conversation marketing.’ It means creating a dialog with customers in which useful information is exchanges to that both parties benefit from the relationship. As trust builds, customers develop loyalty that makes them long-term partners, leading to a more lasting relationship.” (pg. xiii).

Yes, the return metrics are unknown, but perhaps this won’t always be the case.

Email and PPC have a distinct advantage here because we can track click through rates to conversions and the return is often more immediate than other forms of online marketing – and in these times that is a large factor in the decision making process for most companies.