I've spelunked around in the COM header files on MacOS X, and it is fine that there is some kind of COM on X.
But here's the problem. Microsoft Office X has its own implementation of COM bundled into the CFM shared libraries that ship with Office, buried in the depths of the directory structure, private (but shared within Office apps) to Office applications.
The whole point of COM is interapplication communication.
I did my own investigation into Microsoft's support of COM on Macintosh, and the latest official blurb I could find was in the form of an out-of-print book and a MacTech article which included a StuffIt archive of a 'beta' version of the ActiveX SDK (COM's name at that time). Also, at that time Microsoft was hyping support for ActiveX/COM brower plug-ins.
Summary: the great thing about standards is that there are so many to choose from.
Hopefully the new version of Office for OS X will either expose the SDK interface publicly, or utilize the COM headers/API (which you've documented in this article) included in the Apple Developer tools.