My KM Column article for this month explores the topic of CMS interoperability. To quote:

While the goal of interoperability between content management systems (CMS) is an important one, it is limited by the lack of standards relating to content management. At present, there are a range of narrowly-focused specifications in the marketplace, but these address only specific aspects of system interoperability.

A number of initiatives are under way to address CMS interoperability, but these are in their formative stages, and it is expected that at least several years will be required before widely-accepted CMS standards are developed.