There are a few efforts to develop crossovers between .Net and Ruby, but Ruby.NET one that is creating a compiler for the Ruby language that targets the .NET CLR in much the same way as JRuby targets the Java Virtual Machine. This particular implementation is unique in that it can pass all 871 tests in the samples/test.rb of Ruby 1.8.2.

We are pleased to announce the preliminary Beta release of the Gardens Point Ruby.NET compiler. Note: this is not just a Ruby/.NET bridge, nor a Ruby Interpreter implemented on .NET, but a true .NET compiler. The compiler can be used to statically compile a Ruby source file into a verifiable .NET v2.0 assembly or it can be used to directly execute a Ruby source file (compile, load and execute).

Full source is available too.