The year in Twitter trends: from #GulfOilSpill to #InHighSchool and #Iran

Over the past year, one good way to understand what people in the world are talking about has been to follow the trending topics on Twitter, usually preceded by a hashtag (#). From movies, to revolutions and natural disasters ? love it or hate it ? Twitter helped the world understand its own conversations in 2010. We take a look at some of the trending topics of the year.