twitter is just asymmetrical chat. it's almost exactly the same as the way many people have been using irc since the '90s. you idle most of the time and then every once in a while you say something. a little while later, someone else, who has been idling most of the time, reads what you wrote and maybe responds. a little while later you read what that other person wrote. my twitter usage pattern is basically to have twenty or thirty such time-delayed conversations taking place at once, basically forever.
analogy: the literary/screenwriting cliche of two individuals who carry out a chess game over a long period of time, pausing between moves to go about their lives. think of the scene in 'blade runner' between mr. tyrell and the guy from newhart.