It’s happened to me too: I’m angry, or upset, or excited about something. I go on Twitter. I’ve got stuff to say. It’s more than will fit in the 140-character limit, but I don’t have the time or energy to write a blog post. So I just write a tweet. And then another, and another. I’ve seen other people doing this, and I’m fine with it. But for a while now I’ve seen people doing something more planned, numbering their tweets.