According to a research study performed by the Pew Internet and American Life Project:
Some 19% of internet users now say they use Twitter or another service to share updates about themselves, or to see updates about others. This represents a significant increase over previous surveys in December 2008 and April 2009, when 11% of internet users said they use a status-update service.
The median age of a Twitter user is 31, which has remained stable over the past year. The median age for MySpace is now 26, down from 27 in May 2008, and the median age for LinkedIn is now 39, down from 40. Facebook, however, is graying a bit: the median age for this social network site is now 33, up from 26 in May 2008.
Read more at: Twitter and Status Updating
