The UK Telegraph is reporting that, along with the announcements at Apple’s upcoming (rumored) September iPhone event, Apple will lift the lid on an update to AirPlay that they are calling AirPlay Direct.
AirPlay direct would stream music using from the iOS device using cellular data and AirPlay speakers. Great if you have an unlimited data plan (guilty), less so if you don’t.
Given that AirPlay speakers connect to wi-fi, this probably means that AirPlay Direct simply creates an ad-hoc wi-fi network that the speakers can access. [Source]