After a lot of work and great deal of waiting, it looks like the Mono 1.0 has finally been released. Mono brings the .Net framework - a Microsoft technology - to Linux.
Mono includes a C# compiler, a .Net-compatible runtime and two stacks of APIs (application programming interfaces). The first stack is a Mono stack that takes advantage of Linux; the other is compatible with the Microsoft .Net Framework 1.1, which provides support for ASP.Net, ADO.Net and other components. Mono 1.0 also incorporates such key .Net-compliant components as a portable execution system that includes just-in-time and pre-compilation support.
More here.