GitHub has launched documentation for API v3, introducing support for new Issue resources such as Labels, Issue Comments, Milestones, and Events, while also providing full Gist support. This update signifies a shift towards REST conventions, simplifying URL structures and ensuring more consistent resource handling, with URLs returned in the resource fields to ease client-side operations. API v3 exclusively uses JSON for requests and responses due to its ease of parsing and compactness compared to XML. The new system also introduces a rate limiting mechanism, allowing a daily cap of 5,000 requests to manage API usage more effectively. Transition plans from API v2 to v3 are in place, with ongoing collaboration with GitHub library communities to ensure compatibility with new endpoints, and any breaking changes during the beta phase will be documented.