Do you need your own IDE for your project’s domain specific language? One option is Visual Studio Shell, but that is often far too massive to deploy and can be difficult to work with. A lightweight alternative is the Gemini framework by Tim Jones.
ScriptCS enables developers to write C# applications using a simple text editor. Compilation is performed by Roslyn and package management by NuGet.
Roslyn, Microsoft's "compiler as a service", has been updated this week with a September 2012 CTP. This release adds support for Visual Studio 2012 (while dropping Visual Studio 2010), introduces new language features for VB and C#, and includes several updates to the APIs.
Microsoft's Dustin Campbell recently presented a survey of Project Roslyn and provided a demonstration of sample code showing how the project enables Visual Studio to refactor code according to user-defined behaviors.