I am currently working on the CrossPlatformLightweightComponents system, something similar to ComponentObjectModel and XpCom, but relying more on DoTheSimplestThingThatCouldPossiblyWork. See more at http://xplc.sourceforge.net/ (yes, it is OpenSource).
We (the Ludus Design people) released the source code to Quadra under an OpenSource license. See http://quadra.sourceforge.net/
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