With this version of the Dart SDK, we’ve made several improvements and added many features:

With this version of the Dart SDK, we’ve made several improvements and added many features: 

- A faster Dart Virtual Machine that on some Octane tests outperforms even V8. 
- A new Dart to JavaScript translator that generates fast and compact output.
- An HTML library that works transparently on modern browsers.
- A library to interoperate with JavaScript code.
- An easy to use editor.
- Pub, a new package manager
- Dartium, a Chromium build with native Dart support.
- A server-side I/O library.
- A language specification describing the Dart semantics, including new features.

Originally shared by Dart
http://news.dartlang.org/2012/10/dart-m1-release.html