I'm just repeating what was on MS's xml blog, as well as Don XML , but it's worth repeating. Don has created an extension for Visual Studio which allows you to execute an XPath query against an XML file. Other utilities allow it, so I'm surprised that MS didn't already include this. Thanks Don for making our lives easier.
Also, the other “take away” here is that he provides the source code he used to do this. If you are creative, this example can open the doors to many new extensions. Start brainstorming!