From the make.wordpress.org blog:
Today, I can finally announce the release of version 1.2 of the WP REST API.
A short nine months after our last release we have support for Cross-Origin Resource Sharing, full request hijacking, JSON encode/decode errors, and a swarm of bug fixes.
Rachel, Ryan and team plan to release version 2.0 next month, and the REST API is rumored to go into WordPress core later in the year.