It seems like the hottest thing going.  Everywhere you turn, there is another article on Twitter.  I'm on Twitter (@emcallanan).  But sometimes I wonder, how many people are really using it.  Most of my friends aren't.  My parents definitely aren't.  So is it really effective as a marketing tool?  I guess it depends on who your audience is.  I was intrigued by this article from The Center for Media Research earlier this week.  They quote a Harris Poll showing only 5% of Americans are currently using Twitter.  48% have either a MySpace or Facebook page, although only 16% update it on a daily basis.  There are some other interesting stats that come out of the research - take a look when you have a moment.  And then you can Tweet it to all of your followers!