In this case, the document would be a shared "group". Skype would be the backend application that handles any interaction within the group, but it's the shared

In this case, the document would be a shared "group". Skype would be the backend application that handles any interaction within the group, but it's the shared conversation and simultaneous voice/video chat within that group that the users care about. You'd have to go to the effort of adding your friends' "people" objects to the group at first, of course.