As you can see in the picture, a stable version is tested also on Linux platform with Mono.
The tests performed on Linux includes building the project with NAnt, running NUnit tests and executing the sample application.
Oslo, is the code name of the next generation of Microsoft modeling technologies. You can download and install May 2009 CTP version. I suggest you to experiment preview releases using virtualization software.
Oslo innovates application lifecycle management introducing model driven development (MDD), hence the practical application of concepts from model driven architecture (MDA) and model driven engineering (MDE).
In a nutshell Oslo gives you tools to define application domain's entities and logic (the model). This metadata will be stored in a repository (SQL Server) and used to generate your application.
With this new technology Microsoft gives birth to Quadrant, a visual modeling tool, Intellipad, a textual utility oriented to MDD an M, a new language, underlying the model's definition.
So, if you work with Microsoft's technologies, you've a lot of thing to learn...