Mono version 1.0 was released today. Mono is an open source implementation of the Microsoft .NET Framework. In my opinion, this is the first real big milestone on the road to compile once and run anywhere in the world of .NET. The first version of Mono allows you to host ASP.NET applications on Linux, MacOS X and Windows. The Windows.Forms namespace is not fully implemented yet, so you wont be able to run Windows.Forms applications on Linux and MacOS X yet. The Windows.Forms namespace is slated for completion in the next release of the Mono project.