In a move few would have ever imagined coming to pass, Microsoft is open sourcing more of its .Net developer framework and programming languages.

Company officials announced the move on April 3 at Microsoft's Build 2014 developer conference. Execs also revealed they are partnering with Xamarin to create a new .Net Foundation, which will be responsible for the newly open-sourced bits.

Microsoft already helped create another foundation for open-sourcing its technologies, the Outercurve Foundation. It's not clear why Microsoft didn't simply use Outercurve as the vehicle for this latest round of open-sourcing. Update: Microsoft Developer Division chief Soma Somasegar said Microsoft decided creating a separate, completely .Net-focused foundation would be the quickest and most impactful way to get open-source process for .Net moving. He also said Microsoft is considering how and if to work with Outercurve on this project, or whether it makes more sense to keep the .Net Foundation separate.

Among the 24 current and future technologies Microsoft will be contributing to the .Net Foundation are ASP.Net, the Entity Framework, a preview of the .Net Compiler Platform (codenamed "Roslyn") , the VB and C# programming languages, the .Net Micro Framework, and .Net Rx. Xamarin, a maker of cross-platform mobile development tools, is contributing its MimeKit and Mailkit libraries, Xamarin Mobile, Xamarin Auth and more.

Here's a slide from Build 2014 listing all the open-sourced .Net Foundation technologies (so far):

Going forward, Microsoft expects to release as open source more of its .Net components and libraries via the new foundation. It also is seeking contributions from commercial vendors and members of the .Net community. Members of the .Net Foundation "community"/include Xamarin's Miguel de Icaza, representatives from Glimpse, Umbraco, IdentityMine, GitHub and a handful of other companies.

Microsoft officials say there are more than 6 million developers using .Net, and that there are 1.8 billion installs of .Net across various devices.

Microsoft has open-sourced a number of its developer tools and technologies in recent years. The company has released under various open source licenses the bulk of ASP.NET, MVC, Web API, Entity Framework, SignalR, VS Web Essentials, the Azure software development kit and more.

Microsoft also made available today an end-user preview of the .NET Compiler Platform project, previously known as "Roslyn." Roslyn includes the next versions of the C# and VB compilers , as well as a compiler-as-a-service programming interface. And on April 2, Microsoft execs also announced the company is open sourcing WinJS, its Windows library for JavaScript.