You could get a basic, working social network built for a few hundred bucks, but that wouldn't make it a threat to Facebook. And Diaspora won't be one either, unless they've got a trick up their sleeve.

The only thing that is a threat to Facebook is something that causes them to start hemorrhaging users. But face it, when the average person logs in to Facebook they have new stuff to look at it and people to communicate with. But if they signup and login to Diaspora, there just won't be as much activity, if any. So the average person will go back to Facebook, and stay there, until all of his/her friends move to Diaspora. But they won't, for the same reason. It's just not going to happen unless there is some fundamental change.

The reason Facebook gained users so fast was because they generated incredible amount of buzz by making it exclusive and lauching it at Harvard. If I were diaspora, I would follow the exact same launch plan. However, from what they're saying it sounds like this won't be the plan.

So when they launch they'll have a bunch of hacker types come signup and check it out, and they'll possibly even invite their friends. And a few friends may even join. But those friends (normals) will go back to Facebook simply because there's more stuff to look at and more people to talk with. And that will be the end.