You can get it here
NDoc is one of the newest documentation systems.
Designed for C#, it creates a replica of the renowned MSDN-style documentation using the new slowly-becoming-the-standard XML comments by Microsoft.
To use NDoc with C++ you need Visual Studio 2005 and you need to compile it with the common language runtime enabled (/CLR) and you need to make sure you have the flag on to generate the xml docs, of course :). You also need the CVS version of NDoc currently.
NOTE: Classes without the ref keyword prefixed to them (unmanaged) will show up as structs in NDoc