Date: 2008-11-02 11:52:02 Created: null
Twitter describes itself as a site where you answer the question "What are you doing?".
What you actually do is post texts of 160 characters or less. Incidentally, that's just what fits inside an SMS. As another pure incident, Twitter supports posting by SMS, and also recieving updates the same way.
And they have no ads, and don't charge anything extra for sending or recieving SMS messages.
No idea how they plan to make money.
In any case, they also provide nice badges to put on your site so everyone can see your tweets (that seems to be the party-approved term for a single post) from there. Plus, there's a pretty well-defined API. So if you like reinventing the wheel having full control over things you can create your own connections to Twitter in any way you like. And people have, creating neat-looking applications, scripts and other stuff.
Because I'm stupid I like learning new things, I also rolled my own little Twitter fetcher/interpreter/displayer. You can see it on the index page, in the right-side menu. I have plenty of plans for making it fancier, but we'll see what happens. Once something starts working at all, the pace of development tends to drop ...