[gregcohn]

I think what's important is the predictability and stability of the medium. Quora's recent "feature" is particularly repugnant because they had already achieved relatively wide distribution on the model that people were reading things privately, and then unexpectedly turned this feature on on an opt-out basis.

It's like if the postal mail were suddenly posting your mail history for others to see.

It's equally fine to me if a service starts out as more public -- as imessage did, and going back further, as many instant messaging services did. As long as you know how it works before you start exposing yourself to it, it's not only fine, it becomes a feature you might take advantage of. Like a publicly tweeted @message for example, or calling someone knowing they have callerID.

Of course, I believe privacy has its place too -- an important one. We're working on an app called Burner that generates private phone numbers and will release soon.