Here's a new Ruby implementation on .NET from Wilco Bauwer. He has posted samples for IronRuby, for the .NET Common Language Runtime.

Bauwer's post includes the typical "Hello, world" example -- in this case, it is for the February CTP of Windows Presentation Foundation -- along with downloadable binaries and Ruby scripts. Bauwer also covers how to derive from a .NET type and implement a .NET interface.