<http://schema.org/description>
"Earlier this week, there had been reports of ads appearing on the twitter.com sidebar, but these new Firefox ad/messages spotted by Friendfeed user Alphaxion are without question the ..."^^<http://www.w3.org/2001/XMLSchema#string>
<http://thenextweb.com/2009/07/09/breaking-prominent-twitter-ads-spotted/>