It was about 5 years ago (March of 2002 by my records) that Miguel de Icaza and Sam Ruby tried to convince us to ship our own Ruby runtime for .NET, and we thought it was a swell idea. That was probably before DHH heard of Ruby, but it took us awhile to hire the right people, invent the DLR, and ship our first implementation.
It was surprisingly easy to build it, try it out!
Some companies won't let their engineers develop in Ruby, though. If you are at a company that only sanctions Python (the "other" dynamic language), did you know that you can use Python from Silverlight 1.1? Tim Heuer packaged up this sample from Mark Easton. It shows how to do the obligatory rotating cube using a few lines of Python code. You can get the source code from Tim's site.