OStatus lets people on different social networks follow each other. It applies a group of related protocols (PubSubHubbub, ActivityStreams, Salmon, Portable Contacts, and Webfinger) to this problem in what we believe is a simple and obvious way.
OStatus is a minimal specification for distributed status updates or microblogging. Many social applications can be modelled with status updates, however. Practically any software that generates RSS or Atom feeds could be OStatus-enabled. Travel networks, event invitation systems, wikis, photo-sharing systems, social news sites, social music sites, podcasting servers, blogs, version control systems, and general purpose social networks would all be candidates for OStatus use.
The authors recognize that most of this protocol suite was intended to work together in a natural way. They claim no originality or creativity in connecting their use. The authors hope that the obviousness of some parts of this specification are an argument in favor of its use.