File this under things I probably should have known by now.

If you have gone through all the trouble of marking up all of your classes and methods with XML documentation so everyone who consumes your API has helpful summary and description information, make sure you deploy the .xml file with your compiled library. The documentation information is not embedded in the binary. I knew that the xml was required to generate documentation help files, I did not know that Visual Studio also required them for populating documentation in intellisense and the Object Browser.