A study released today supports the oft stated notion that most of Twitter's 75 million registered users are less than committed to the microblogging site.
The report, compiled by Barracuda Networks Inc., an e-mail and Web security company, concludes that only 21% of people now signed up for the Twitter Inc. service use it regularly.
"Moreover, today there are 34% of users who have not tweeted since they created an account," said Paul Judge, chief research officer at Barracuda Networks, in the report. "While that still seems like a fairly high percentage of inactive accounts," he noted that the percentage of inactive users is down from from 37% in June 2009, "demonstrating that people are becoming more active."
I don't know if that's a concern or not. I think it's common to sign up with a social network to grab one's name but then not use it.
Twitter has a usability issue for new users, too: only followers see your tweets (usually), and newbies have no followers. I've heard the comment more than once, "I tried Twitter. I posted for a few days and nothing happened, so I quit." It's not always obvious that connecting with others is a key first step.