<http://schema.org/topics>
"blogging,news,Social Media,tumblr,web,web 2.0"^^<http://www.w3.org/2001/XMLSchema#string>
<http://mashable.com/2010/03/08/tumblr-revenue/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+Mashable+%28Mashable%29>