What's intriguing to me is that they started with less features. I'll explain.
When some new thing comes onto the scene, like IRC or KaZaA or whatever, it is usually very shaped, the creators have a specific use patten in mind. And so they stock up on all the features that <i>they think you're going to want</i>. Twitter seems different (not using it myself). It comes with <i>less features</i>.
And now, having listened to that talk, I can see that originally it came with no "features" whatsoever beyond the starter "hunch", a sort of an objectified idea.<p>That is what's worth a ponder, IMO.