Personally, I think it's rude to be having two conversations at the same time. Also, I think it's rude to be doing one thing in public and talking on a phone at the same time. People think they can handle both, but they can't.

I have had to stand there waiting for someone to get out of the middle of the aisle, not know their kids are five feet away tearing up the stock, or get their checkbook/money out in line, etc, etc, etc. And while your niece was stunned at what she heard, usually it's the other way around, I hear things people wouldn't talk about one on one in fromt of someone else, but it seems they feel confident that since only one end of the conversation is heard, it's ok.

dl