Darn I was really hoping that I could leverage the same LINQ queries against both SQL and XML smilie
Having read this book and done some fruitless google searches, one thing I don't really see covered is how to easily switch between a SQL data source and an XML Data Source, such as if I were doing a small 'briefcase' or prototype application, vs going live against a Database server.

What's the minimum I would have to change? And what can I do to make a single code base support multiple/switchable mappings?