<http://schema.org/about>
"Alright Twitterers, it's time to add a new hashtag to your tweets and show off how you're making a difference for Earth Day. And you might even win something cool for being, well, cool. EarthTweet is a new tweet-a-thon being held"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.treehugger.com/clean-technology/earthtweet-turns-twitterers-into-earth-day-advocates.html>