I track a bunch goings on for a bunch of vendors. Alfresco, an open source ECM solution, just published a newsletter that talks about the concepts of core vs context. Bill Robinson does a good job of explaining the concepts and applying it to his specific solution.
Moore’s thesis, which would apply to any independent software vendor or development shop, is that you focus your efforts on your core and then collect the context pieces to add. You can add those pieces by building them yourself or buying them from another software vendor. The build-versus-buy scenario pits XYZ’s ability to design its own document repository application – which carries a considerable time commitment and attendant business risks – against the financial commitment of purchasing a proprietary outside product that brings up issues of licensing, integration, etc.