Advertising around stories recommended in social media is more effective

"The overall uplift for brands who advertise around stories recommended in social media is significant. The global online survey showed that people who received news content from a friend or associate via social media, were 19% more likely to recommend the brand that advertised around that story to others and 27% more likely to favour that brand themselves.
More specifically, POWNAR examined case studies including one where a major European tourism board reported notably stronger campaign cut-through with aided ad re-call up 50% and brand favourability up 32% after advertising around news that was shared in social media."
Source:  POWNAR research from CNN, October 2010