Microsoft recently released the August 2010 CTP of F# (pronounced F-Sharp). F# is a functional as well as object-oriented programming language for the .NET Framework. It combines the succinct, expressive and compositional style of functional programming with the runtime, libraries, interoperability, and object model of .NET.
As quoted by Microsoft “The F# August 2010 CTP provides all the tools and resources needed to develop applications with the F# programming language. It is available as an MSI for use with .NET and Visual Studio, and as a ZIP for use with other CLI implementations and platforms, including .NET Compact Framework on Xbox 360, and Mono on Mac, Linux and other platforms”