DotGNU is an abandoned part of the GNU Project that aims to provide a free software replacement for Microsoft's .NET Framework by Free Software Foundation. Other goals of the project are better support for non-Windows platforms and support for more processors.
The main goal of the DotGNU project code base is to provide a class library that is 100% Common Language Specification (CLS) compliant.
Read more about DotGNU: Framework Architecture, Free Software, DotGNU and Microsoft’s Patents