When you operate an API, you need to make sure and communicate with your developer community about what your plans are for the future, so developers can plan their own roadmap, and keep in sync with the coming changes to the API.
In addition to issue management using Github, API providers can use Github to manage their roadmap using the milestones features of the social coding platform. Milestones can be directly related to issues or can be larger goals around where you intend to take your API.
Milestones give developers insight into what the plans are the future of an API, using just a title, description and target date. Milestones are one of the simplest aspects of an API, but can go a long way in creating goodwill with your developers.
API providers have to balance transparency versus giving away information to competitors, something that will take regular consideration. A transparent roadmap for your API will let developers prepare properly, while also letting them know what features are coming in the future--eliminating the possibility of competing with your own ecosystem.
Consider what you can include in your Github roadmap, and using Github for issue management.