Well almost. Until PDC this year LINQ was just an experiment. At PDC it came to the forefront and has garnered rightfully so a lot of attention. I've been using a similar technique for many years. Earlier this year I ported it to C# to take advantage of the .NET framework and the flexibility of C#. My implementation does not do XML and some of the other things that LINQ does, but then again I do not have the ability to modify the language or the compiler.
However if you are interested in trying something simlar out now that can be used in production, or just see how truly flexible .NET and C# are you can check out my SQL in C# article and implementation. Because LINQ progress has been moved up and focused on at PDC I will be no longer developing this library as LINQ will surpass it, however its still useful until LINQ is released, and interesting for those wanting to study C#.