Here’s a link to a post I just finished on ‘How to implement IQueryable’ (create a custom Linq provider).

http://blogs.msdn.com/kevin_halverson/archive/2007/07/10/how-to-implement-iqueryable.aspx

My example project allows you to query the Windows Vista (Desktop) Search engine for files on your local machine.  For example:

        Dim index As New WDSQueryObject

        Dim cutoffDate = #6/28/2007#

        Dim r = From file In index _

                Where file.CreationTime > cutoffDate And _

                file.Name Like “%.exe” _

                Select file.FullName, file.CreationTime