Twitter has finished presenting its money-making plan at an advertising conference in New York, and it's remarkably simple: Stick ads into people's Twitter streams. Where they'll read them like everything else.

Twitter, after all, is nothing if not the preeminent platform for self-promotion; much of the microblogging platform's content is already advertising, in other words, behind the thinnest of veils: promoting one's website, article, book, consulting business, etc.. So it will be awfully hard to notice when Twitter starts inserting sponsored tweets into search results and, eventually, regular streams, as the startup announced it would do at an Ad Age event and in the New York Times.

Of course, it helps that they'll uniquely formatted, according to Twitter's demonstration, as photographed by interactive marketer David Berkowitz:

The only questions are whether the ads will attract clicks, and thus profits for Twitter, when the rest of the service's content is so self promotional—and why it took Twitter four goddamned years to come up with such a simple business model. I mean, really.