This issue will be used as a roadmap for the first stage of the development of the Social API, in which the project will seek for harmonizing Social Networking functionality in Drupal
For more info about how it's architecture, refer to this node
This roadmap provides an overview of where the Social API and its dependencies are headed and how they will get there.
Social Networking Plugins
Current projects to port
These are some projects (by social networking) that are start points of functionality for the sub-modules. We can even work alongside the maintainers in most of the cases to adapt their projects to the Social API.
This comment has a good overview of available plugin-related modules