GNU Social should support the ActivityPub standard for federated social networking and social API. The standard has been in development at the W3C for 2 years. It's based on the work that I and others have done to upgrade and streamline OStatus. Other social applications like pump.io and GNU MediaGoblin are working to implement ActivityPub.
There is some more information on the state of the ActivityPub network on the W3C wiki. We're trying to get everyone involved in federated social networking to rally around this standard and get a truly federated network working.