Twitter's business model?

Mashable has a good summary of the discussions taking place on the internet over the past few days about whether Twitter has a business model:

While the tech blogosphere has been gearing up for the post holiday rush of news, it has yet to have descended upon us. As such, we’ve all been seemingly enraptured by Allen Stern’s question today: Is Twitter F’d? Many from the so-called “A-List” have weighed in with a response, and here are some of the ideas:

Jason Calacanis: “Imagine if every 10th, 20th, or 100th tweet was an advertisement. Would that be so horrible? No, not at all. ”

Dave Winer: “Okay, so you can’t imagine Twitter getting into the hardware business or being a cell phone service provider. But what if one of those did a deal with Twitter, or even bought Twitter?”

Jason Calacanis: “Users would be perfectly fine if every 100-200 or so SMS Tweets they got an advertisement.”

Robert Scoble: “Glad to see that Twitter has a business model. I’d pay for it to deliver all of my messages! “

Read more here (including some of Mashable's suggestions).