LinqToCodeModel is now on available on Code Gallery. LinqToCodeModel, created by Pablo Galiano of Clarius, is a sample library on top of the Visual Studio API class: EnvDTE.FileCodeModel. LinqToCodeModel provides LINQ queries and functionality for the FileCodeModel object, and will work when using the DTE FileCodeModel object within Packages via the VS SDK or within Add-ins.
Pablo also included screencast video (WMV) download on the Code Gallery page as an overview demo of LinqToCodeModel.
To show a simple sample of LinqToCodeModel in action, there is an updated version of SourceCodeOutliner Lite, a modified version of The Source Code Outliner Lite walkthrough based on Quan To's blog post Building your own Visual Studio Source Code Outliner extension.