WebKit, V8, and Microsoft Edge have each gotten a little closer to supporting the full ES2015 (ES6) spec and beyond. WebKit was the first browser engine to reach 100% on the Kangax Compatibility Table while V8 and Edge each added more features to their implementations.
Node.js 6.0 has been released, becoming the new current version. It comes with performance improvements, better test and documentation coverage, better security and wide support for ES2015.
Microsoft has released version 1.7 of TypeScript, which enables async/await for ES6 targets and introduces a polymorphic this type.
Microsoft has released TypeScript 1.5, dramatically improving ES6 transpilation capabilities.
The General Assembly of Ecma International has announced the approval of ECMA-262 6th edition, which is the Language Specification of ECMAScript 6 (ES6), also known as ECMAScript 2015.
Google has released Chrome 44 beta: with updates including new ES6 features and improved notification capabilities. The latest beta release for the OS brings computed property names, allowing expression for property names in object literals and class literals.
Microsoft Edge started as a IE fork but later departed considerably from it in an attempt to break with the past and legacy Internet technologies, removing 200K LoC but adding other 300K. Microsoft says they want “better interoperability with other modern browsers, improved performance, security & reliability, and reduced code complexity.”
Node.js has released version 0.12, its first significant release since 2013's 0.10. The much-anticipated version 0.12, once described as "imminent" in January 2014, comes with a raft of Module and JS API changes, an updated version of V8, and many debugging enhancements. Significantly, it also comes with initial support for ECMAScript Internationalization API 1.0 (ECMA-402).
The io.js team has released version 1.0 -- but the versioning does not suggest the platform is "production ready." Despite overtaking Node, io.js clarifies the release in its own FAQ: "The choice to release as 1.0.x was not to signify that io.js should be considered production-ready, but because it was a significant enough release from Node.js to warrant a major version increment," it says.