I think he was talking about applications that allow interaction between users, person to person. For example, he mentioned "Business card apps". I don't know what he is referring to, but maybe there is an app that allows you to beam (through IR or BT) your "ebusiness card" to another iPhone user. If the application is proprietary and only works between iPhones people will see it as an advantage to have an iPhone to be amongst the in crowd. Just an example of what I think he is referring to.