I ported a bunch of COM to Linux in the late 1990's. Not DCOM with the full RPC, but just in-process COM. I had .so shared libs with DllMain and DllCanUnload now in them, I had CoCreateClass, I had a significant part of the registry API implemented in terms of a text file store (HKEY_LOCAL_USER being in the home directory, HKEY_LOCAL_MACHINE somewhere in /etc, ...) and such. IUnknown, QueryInterface, AddRef, Release, ...
Netscape did that with XPCOM [1] they once thought that this is a good idea - i guess for versioning of interfaces; nowadays firefox has moved on from this.
Haha, funny enough our company did this as well - we had lots of legacy C++ code using COM and wanted to port to Linux. It was not that hard after all.
