Here is what they have to say for themselves:
We are pleased to announce the release of a new Beta (version 0.6) of the Gardens Point Ruby.NET compiler. Implementation is not yet complete but we have now implemented the vast majority of Ruby's builtin classes and modules. We have fixed large numbers of existing bugs, but many still remain. We have not yet implemented continuations or Ruby threads but support most other language features.
In addition to passing all 871 tests in the samples/test.rb installation test suite of Ruby 1.8.2, we are now able to support the standard Ruby test unit library and pass most of the 1864 assertions in the test/ruby test directory.
We have just started work on getting Ruby on Rails to run on Ruby.NET and have started work on adding interoperability features to allow .NET programs written in other languages to conveniently use Ruby components and vice versa. We hope to include some of these features in the next public release.
Our plan now is to perform public releases more frequently, approximately once a month. Once we have stabilized the major design choices (including those required for interop) we will move to a more traditional open source type model where others can contribute directly to the code base. We expect this to happen in the second half of this year.
They do not have closures yet, so how will they run Rails? It would appear that the JRuby team is still much further ahead, but will the .NET people catch up? I look forward to playing around with the new Ruby.NET regardless, but it doesn't sound like it will be useful to me...yet.