Write (.Net library) once, use everywhere (in .Net world)? The Portable Library Tools CTP Released. (Think “Reusing/Sharing the same Project between SilverLight, XNA, Windows Phone, etc” or “DRY .Net Project Style” )
“Portable Library Tools is a new Visual Studio add-in from Microsoft that enables you to create C# and Visual Basic libraries that run on a variety of .NET-based platforms without recompilation.
Simplify code sharing
No more complicated build scripts or #defines, and stop copying and pasting code; portable libraries enable you to easily share code between apps that target different platforms.
Share between platforms
Create a Portable Library project and reference it from any .NET Framework, Silverlight, Windows Phone or XNA project.
Interesting. I like seeing this formalized and supported.
Note: Requires VS2010 SP1 Beta