Not at the moment of the conversation, but there's nothing stopping one of the people there from blogging about it once they get home (think Silicon Valley "overheard" product leaks).

The fact that a piece of information passes through a volatile medium before ending up in a more permanent form doesn't change the value or ownership of the information.

On a tangent, Google Glass passive audio and video recordings will be much more damaging to one's privacy than photos shared intentionally by friends.