Ximian launched the Mono project [L1 ] "to create an open source implementation of the .NET Development Framework.

Mono includes: a compiler for the C# language, a runtime for the Common Language Infrastructure (also referred as the CLR) and a set of class libraries. . . ."

elfring 2003-11-04 Would you like to see TCL on the page "Compilers for other languages" [L2 ]?

According to FAQ, Mono is basically a development framework which provides a Unix developer the means to build and deploy cross-platform .NET applications. It runs on various mainframe and desktop platforms (such OSes as Linux, Solaris, MacOS X, FreeBSD, OpenBSD, NetBSD, Microsoft Windows, and HP-UX and hardwares such as 390s, SPARC, PowerPC, x86 (both 32 and 64 bit), IA64, ARM, and HP-PA).

Currently, the mono-project web site lists support of these languages:

Other languages, like Ruby, also have projects going on to incorporate support.