The XML documentation generated by the compiler must be parsed by tools such as NDoc (which I help develop). To integrate the help into VS.NET, you actually have to do quite a bit of work that involves the Help 2 system. You can find more information on MSDN by searching for "VSHIK", the Visual Studio Help Integration Kit. As far as "tooltip help" when you're typing in the VS.NET source window, the XML file for the assembly merely has to be in the same directory as the assembly itself. VS.NET will see that XML file and show the appropriate help based on what you're typing (class, method, parameter, property, etc.). It will not automatically integrate this into the help system (dynamic help, table of contents, index, and search), however.
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