XText is a great editor and language manufacture for the DSLs in EClipse. I thought that Intellipad is the equivalent in the .NET world, of course as all I get disappointed when Microsoft announce that it would be part of SQL Server.
Now if I need to create a DSL that runs on the .NET environment with editor that support coloring, intelliscence, errors ... (the editor runs outside the visual studio is a plus, WPF editor is a plus), what tools I have to look for ?
Microsoft "M" is indeed the answer to Eclipse Xtext. Just to compare. Xtext is mature, "M" is CTP. Xtext has twice as many features, but "M" offers some that Xtext dont. Especially the debugging-capabilities and the dynamic parser (no codegen needed).
Rest assured, that you'll be able to use DSLs from "SQL Server Modelling" without having to run it in the relational kernel of SQL Server.
BTW, the Entity Framework is developed from within the same group. Isn't it also available in .NET?