According to Pew, about 19% of Internet users post updates about themselves or read updates about other people on Twitter or other services, up from 11% both this past April and in December 2008.
Pew also found that 35% of Internet users who already use other social-networking sites such as Facebook, MySpace and LinkedIn are likely to also use Twitter, as opposed to only 6% of non-social-network users.
On the mobile front, as of September, Pew found that 54% of Internet users have a wireless connection via laptops, cell phones, game consoles, or other mobile devices, and 25% of those users use Twitter or a similar service, up from 14% last December. For those with non-wireless connections, the respective figures were just 8% and 6%.
Pew also examined the median ages for users of social-networking sites and found that Twitter remained steady at 31, MySpace dropped to 26 from 27 in May 2008, LinkedIn dropped to 39 from 40 and Facebook rose dramatically to 33 from 26.
The results from Twitter and Status Updating, Fall 2009 are based on data from telephone interviews conducted by Princeton Survey Research International from Aug. 18-Sept. 14 among a sample of 2,253 adults 18 and older.