It's not really different. In both cases, if you knew your boss could've known, you wouldn't have said it. In both cases, you were in trouble because your talk was not as private as you thought it was.

The real differences lies in the understanding of the risks. The "brother bartender" is something most can understand. We all understand that talking in public areas carries a risk of being overheard, and we tune our speech accordingly. However, we don't all understand the risks associated with Facebook and many other services "in the cloud". This means a higher risk of being careless (and hurt yourself in the process).

Until we understand privacy risks associated with internet services as well as those associated with physical interaction, we will have unexpected problems. I'm confident that people will learn anyway. I just hope they don't learn the hard way.