The main problem is lack of support, it is a very big effort to create an OS and it is very easy to turn attention to other stuff.
Linux and BSD distributions wouldn't have reached the state they enjoy nowadays, without the help of the existing UNIX toolset and investment of companies interested in seeing the projects succeed.
D - Xomb - http://wiki.xomb.org/index.php?title=Main_Page
Go - TinyGo - http://code.google.com/p/tinygo/
C# - Singularity - http://singularity.codeplex.com/, Cosmos - http://cosmos.codeplex.com/
The main problem is lack of support, it is a very big effort to create an OS and it is very easy to turn attention to other stuff.
Linux and BSD distributions wouldn't have reached the state they enjoy nowadays, without the help of the existing UNIX toolset and investment of companies interested in seeing the projects succeed.