One of my more inverted convictions is that one way you can tell when a piece of technology is crossing the chasm is when it gets an undo feature. Most applications, at the beginning, don’t have an undo feature. What you do is what you’re stuck with. Make a mistake, and you’re done.
Early adopters can live with not having an Undo feature. They’re used to technology that breaks, or that starts working and then stops, so the Undo is neat to have, but not something that stops them from using a service.
Real people feel differently. Real people can’t live with products or services that do useful and important things, but where accidents are irreversible. With that in mind, watch for when something gets an undo feature, and you have a sign that it’s no longer just the playing of early adopters, and it has become more mass market.