Nemerle (.NET 4.5, Visual Studio 2012)

Nemerle is a high-level statically-typed programming language for the .NET platform. It offers functional, object-oriented and imperative features. It has a simple C#-like syntax and a powerful meta-programming system.
Features that come from the functional land are variants, pattern matching, type inference and parameter polymorphism (aka generics). The meta-programming system allows great compiler extensibility, embedding domain specific languages, partial evaluation and aspect-oriented programming.
To find out more, please visit: http://nemerle.org/