The number of Americans tweeting, or using another status-updating service similar to Twitter, has grown rapidly over the course of the year. Surveys conducted by Pew Research in December 2008 and April 2009 found that 11% of Americans who use the internet were on Twitter or a similar service. Today, nearly one-in-five online Americans (19%) are tweeting. Three groups are most responsible for the growth in tweeters: social networkers (35% tweet), mobile internet users (25% tweet) and young adults (37% of internet users ages 18 to 24 tweet). The median age of a Twitter user is age 31. By comparison, the median age for a Facebook user is age 33 (up from 26 in May 2008). Read More