<http://schema.org/description>
"It's been a few days since twitter announced it would ban all advertising  within user's twitter streams aside from its own. The only advertising twitter would accept was advertising ..."^^<http://www.w3.org/2001/XMLSchema#string>
<http://thenextweb.com/2010/05/27/you-know-its-quite-possible-that-all-these-in-stream-twitter-ad-networks-are-here-to-stay/>