Over at the Twitter blog, it’s Chief Scientist on Wednesday released a list of the top trending topics on the site in 2009.  He writes:

Twitter’s Trending Topics helped us understand what was happening around the world showing us that people everywhere can be united in concern around important events; excited about a new movie; or geek-out about a major new technology.

And further:

Among all the keywords, hashtags, and phrases that proliferated throughout the year, one topic surfaced repeatedly. Twitter users found the Iranian elections the most engaging topic of the year. The terms #iranelection, Iran and Tehran were all in the top-21 of Trending Topics, and #iranelection finished in a close second behind the regular weekly favorite #musicmonday.

Hat tip to Digital Media Wire.