Twitter is now a part of my daystream. I check in first thing every morning, and return at least once an hour until bedtime. I'm offline, of course, during movies, and don't even usually take my iPhone. The only tweeting I've done with mobile devices was when our internet went down one day, and when my laptop was lost in Cannes. But you can be sure that before I write the next three paragraphs I will tweet something.
Twitter for me performs the function of a running conversation.