"At Moz, we strive to include social media metadata in all new pieces of content that we publish. This allows us to optimize for sharing Twitter, Facebook, Google+ and Pinerest by defining exactly how titles, descriptions, images and more appear in social streams.
Think of it as conversion rate optimization for social exposure.
The implications for SEO are also significant. We know from experience and studies that the right data, includingoptimized images, helps content to spread, which often leads to increased links and mentions".
Read More: http://moz.com/blog/meta-data-templates-123