[cageface]

Mac OS X has nothing that even comes close to COM.

Because it doesn't need something like COM. As is so often the case, Apple has made some radical simplifications. ObjC has its faults but the C/ObjC/ObjC++ stack covers a lot of ground with minimal mental overhead.

[pjmlp]

COM can be used by any language and allows software components, object based, to be "easily" shared among languages.

How does it work in Mac OS X?

[cageface]

You either write to the underlying C API or you use ObjC.

[gaius]

Right, but Apple once thought it needed OpenDoc.