Boundaries

I had an interesting discussion with a friend earlier today about the boundaries between public and private, and the non-obvious line where venting and asking friends for help and support shades into talking about someone else's business, perhaps even more so online. When does your need for support run into someone else's wish for privacy? I've had this come up in my life often enough that I've put a lot of thought into it, but I thought this would also be a good place to ask other people's experiences - please feel free to add anything you like in comments.

[Poll #830069]