eMarketer Mashable Twitterers 6 million 200 million registered users in 2009 post six million in 2008 Twitter has an estimated six million users Nielson Online The counterpoint to this observation 200 million registered users in 2009 Mashable Mashable 6 million twitter users in 2008 published http://mashable.com/2009/04/28/twitter-active-users/ Over 10 million people Mashable How Many People Actually Use Twitter? published How Many People Actually Use Twitter? Mashable Mashable Nielson Online post http://mashable.com/2009/04/28/twitter-active-users/ Twitter has an estimated 6 million users reported that How Many People Actually Use Twitter? reported that six million users today some are passive Twitter users Adam Ostrow