Pew Internet & American Life Project Studies Twitter

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.