I'll buy this formulation. But from the cheap seats, it all comes down to the same thing. Whether it's in the platform, where all apps can make use of the functionality, or simply a set of conventions that enough application developers adopt so that the web of cooperating applications acts like a platform, we get what we want. (Some of the difference between what I say and "in the OS" is the looser definition of "the OS" that you can take from Unix/Linux and the Internet. I like to say that some OSes are "one ring to rule them all" and others are "small pieces loosely joined." In a "small pieces loosely joined" OS, features aren't in the OS so much as they are in the conventions that govern inter-application interactions. I use the word "conventions" rather than "rules" because there is no cop to enforce them. No "operating system" specifies the interaction between internet end points, but Jon Postel's "robustness principle" says a lot about how end points *ought* to act.)
Message aware might capture a lot of this functionality, but I'm not sure all of it comes down to messaging.
Finally, wrt IPv6 broadcast, you should look at the clever way that rendezvous uses local multicast with the DNS protocol to achieve ad hoc networking.