The Dart programming language: in its early stages

Dart is a new class-based programming language for creating structured web applications. Developed with the goals of simplicity, efficiency, and scalability, the Dart language combines powerful new language features with familiar language constructs into a clear, readable syntax.

Official Site: http://www.dartlang.org/

Try Dart Here (Online): http://try.dartlang.org/

Also it is open-source: http://code.google.com/p/dart/