Imagine a simple Twitter-like system built on top of this, for example. Each web client would function as a store-and-forward. Every time you connect with a friend, both parties would reconcile the latest posts from all friends that they share in common. In this way, information on social networks could be disseminated rapidly and efficiently with no centralisation whatsoever.
Seems to me like just two other bits of technology would be needed for this: ubiquitous dual-key authentication, and a good UID system. I don't think either of those would be a problem, and I really hope somebody does this, since centralised social networks bother me more than a little bit.
It's not done yet, but what ever is? ;)
It works by building a system of distributed identity and messages around GPG signed JSON, and can be distributed over any medium. Right now, It's web-based and HTTPS calls, but I'm actively looking for a good webrtc solution I can use without leaking users IPs and other data.
There's some information about it at Tavern.com
If anyone's interested, I'd love to work with you to figure out how to make it better ;)
As for UID, if you just want some kind of unique identifier, you can just use a public RSA key. If you want an unique but readable name (like a nickname), you need something more sofisticated. A possible approach is Namecoin's, which tries to guarantee unique but decentralized domains.
Because of the custom program model, Grimwire's concerns include program lifecycle, resource management, permissioning, peer connectivity, and UI toolset, so that's why we call it an OS.