OK. But remember that most of the world actually hasn’t heard of, let alone used, the service. So exposure like this “Nightline” episode, which aired last night and reached millions of people, means… something.

My favorite bit comes right at the beginning, when host Martin Bashir asks, “What is it? Well, I don’t really know, because I don’t do it.” (By the way, a note to ABC News: You guys gotta make your video embeddable).

And while we’re on the topic of Twitter hype, here’s my question for proponents of the “Twitter is the next Google/YouTube/whatever” meme. I certainly think that the service could be a big deal (maybe). But can you explain how it reaches the critical mass of a Google (GOOG) or YouTube?

Because everyone looks for something. And just about everyone wants to watch a video of something. But people who want to broadcast their thoughts or actions to the rest of the world–that’s always going to be a subset of the general population, right?