John Lam, the creator of RubyCLR, has accepted a position at Microsoft. While he hasn't yet revealed his new duties, he has stated that he will not leave the Ruby community.
First released in January of 2006, RubyCLR is a "high performance bridge between Ruby and .NET". The current version is only available as source code and will need to be compiled using VS 2005. Currently the project's wiki site is down, so documentation is hard to come by.
With his January 2007 start date fast approaching, Mr. Lam has already started looking for people to help drive the RubyCLR project. Interested people can find his contact information on his web log.
This isn't the first time Microsoft has tapped a dynamic programming language expert. It wasn't too long ago that Jim Hugunin of IronPython fame joined Microsoft.