That is correct. Mostly. The cool thing about C# is that you can put that documentation inline with your code. Reduces redundecy and work for the developer.
NDoc has the ability to read those comments through the assembly and rip documentation that way. Realizing the shortcoming of VB and recognizing that there are many VB developers who might want to take advantage of this functionality, the NDoc team gave users the ability to create documentation from an assembly and a seperate XML file.
All NDoc does is interpret the assembly and compile the comments into a very slick HTML, LaTeX, CHM, and/or several other formats, document that you can use to document all of the functionality in you own asemblies.
Doxygen does a similiar thing only it can actually create the documentation without the developer giving it any anyput. It is very well tested for C/C++ and it looks like it might even work for C# to a certian extent.
What I am looking for is a one step process that will create documentation for me. The way I do it now, I have a program that goes through the code, rips special comments and documents the structure, and then creates a sepecially formatted XML file. This file, along with the assembly is then loaded into NDoc and creates a wicked awsome refernece document I can publish on the server or whatever for other developers of my assemblies.