I joined twitter on 12 March 2007 - http://whendidyoujointwitter.com ISTR hearing about it on IRC, or skype, or something during SXSW 4 years ago. The appeal lasted for 3-4 months until the limitations started to annoy me. At which point I began to use it purely as a broadcast mechanism pointing to other things and a tool for moving status from one place to another. (eg Buzz to Facebook).