One in five online Americans feels the need to tell the world what they're up to, according to the Pew Internet & American Life Project.
Some 19 percent of internet users now say they use Twitter or another service to share updates about themselves, or to see updates about others - well up from April, when 11 percent of internet users said they use a status-update service.
Tweeters fall into three main groups, according to the company - social network website users, those who connect to the internet via mobile devices, and younger internet users, under 44.
They're a gadget-happy lot - the more devices someone owns, the more likely they are to use Twitter. Thirty-nine percent of internet users with four or more internet-connected devices (such as a laptop, cell phone, game console, or Kindle) use Twitter, compared with just ten percent of users with one device.
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. Facebookers are getting older - 33, up from 26 in May 2008, but LinkdIn is the one for the real wrinklies, with a median age of 40.