I just read Bill Joy's article (and ping is right, Virgina Postrel's response does a good job of highlighting the holes), but there's one of his basic values which I do not understand: What's up with his affinity for the "human species"?
Don't get me wrong, some of my best friends are humans. And they're incredibly beautiful creations, too. But does that give them a permanent or exclusive right to existance on this plane? I'm not so sure about that.
Things die. I feel humans will too, sooner or later. I do, however, hold out a hope that the spark of life which flourished on this planet will not be extinguished by our leave. But if something else comes along which is sophisticated and evolved enough to take our place... Why shouldn't it?
I guess if I were robbed of the chance to see what my progeny and I would live to accomplish, I'd probably be unhappy about it, because I don't think of myself as a force of evil. But given the choice between being survived by my own creations, or nuclear irradation, I'd choose robot takeover any day of the week.