The idea of Microsoft releasing Visual Studio for Unix and Linux was once - quite literally - a joke.

Not only was Visual Studio only built for Windows, but Microsoft's licensing had prevented people using its premier development environment with non-Windows platforms.

Now, there's a little less to laugh about. Microsoft partner Novell has delivered a plug-in designed to help Visual Studio developers easily build, debug, test, and port applications built using C# in Visual Studio 2005 to Linux, Unix, and OS X. The plug-in has Microsoft's full blessing.

Mono Tools for Visual Studio, released today, lets developers use their existing knowledge of the IDE's code and tools to target these non-Windows platforms. An update is already in the works for Visual Studio 2008 with support also planned for Apple's iPhone.

The plug-in targets Windows developers who want to build .NET applications, build appliances, and cloud images using Mono for Linux, Unix, and OS X. It's based on Mono, the open-source implementation of .NET led by Miguel de Icaza and bought by Novell several years back.

Mono Tools for Visual Studio includes a debugging engine, integration with Visual Studio pull-down menus, and out-of-the box integration with SuSE Studio Online, a Novell service that lets you roll your own Linux distro by wrapping up packages, database, files and configuration for use on things like appliances.

You could target non-Windows platforms in Visual Studio before, but the set up was cumbersome and there was no standard way to build and transfer code between Windows and non-Windows environments. The work in Mono Tools for Visual Studio has focused on ASP.NET and Windows Forms, rather than Mono's Graphical User Interface Toolkit - GTK#.

de Icaza told The Reg: "We are looking at bringing Windows developers to Linux."

Microsoft said in a statement Mono Tools for Visual Studio enriched the Visual Studio ecosystem and made it possible for developers targeting .NET to gain "additional value" from their Microsoft tools and skills.

Mono Tools for Visual Studio is available in three editions: Professional priced $99 that targets individuals, Enterprise for one developer in an organization is priced $249, and Ultimate priced $2,499 for an limited commercial license to redistribute Mono on Windows, Linux, and Mac OS X. That includes five enterprise developer licenses. ®