It's a bit confusing, but basically right now there are two Angular products: AngularJS 1.x and AngularDart. These two efforts are supported by completely separate teams. Now the JS and Dart teams are merging and the new Angular 2.0 will be written in TypeScript and transcompiled down to ES6, ES5, and Dart. So while it may look like jumping around, the message seems to be consolidation.