(Adapted from a post to the internal discussion board for my winter 2010 Medill course, “How 21st Century Media Work”)

“I’m convinced Twitter is here to stay,” David Carr writes in Sunday’s New York Times. “And I’m not alone.”

I’m thinking he’s probably right, and for the same reason: “the real value of the service is listening to a collective voice.”

It didn’t start that way for me any more than it did for Carr. It was July 16, 2007, when the Tribune’s Brad Moore told me about a new text-messaging service that RedEye had started to play with. He was reporting to me as its general manager then, and his folks were doing their best to stay on top of communication trends that its twentysomething readers were starting to embrace.

As it happened, I wouldn’t even join Facebook till August of that year, and FriendFeed, Fark, and Digg were even further in the future. Anyway, I signed up, though I didn’t get around to “tweeting” for another month. And it wasn’t until 2008, when the interns that I’d hired to build the Tribune’s social media profile started to show how Facebook + Twitter + Digg = Pageviews, that it dawned on me that those 140-character messages might be a big deal. So I opened a second account — @YoungOwen, the one I’m still using today, since I have been unsuccessful in getting Twitter to untether my first one from my extinct Tribune mobile phone.

And sure enough, I’ve learned enough from tweeting and reading other people’s tweets to see that, like fax machines and filing cabinets, this service is something that’s not going away. As Carr observes, it has become part of the infrastructure; he quotes Clay Shirky: “Anything that is useful to both dissidents in Iran and Martha Stewart has a lot going for it.”

It goes (almost) without saying that the precise business model hasn’t quite emerged. But let me be the one millionth person to note that countless companies are piggybacking on it, mining the real-time “statusphere” or “Twitterstream” to keep track of their brands, promote themselves, or find potential customers. All of those uses are applicable to journalists and media companies as well as technologists and gossips.

It is a peculiar and arcane skill, tweeting something that might be of interest to people you don’t know (which can happen all the time with the right #hashtag). But since journalists need to do that nearly every day in their “real lives,” it seems also to be a useful one.

If you’re not on Twitter, you could do worse than to follow Carr (@carr2n) and the nine users he highlights. You might well wind up deciding to tweet what you learn.