Thanks for the suggestion! At the moment, we have our hands full with the current PKP suite, but we do have tentative plans to split the PKP platform (i.e. the shared codebase between the three major products) into a separate source code tree to improve maintainability. This will also give us a major starting point for additional projects, should demand and manpower allow it.
There are also many features that OJS and OCS in particular touch on, such as discussion forums (in the form of the threaded article discussion feature) and mailing lists (in the form of the Notify Users feature) that could be fleshed out much further; in these situations, it's important to choose between two approaches: integrate or build.
Since there are so many excellent open-source forums, CMSs, mailing list servers, etc., the best approach might be to foster closer integration between these systems rather than developing them from scratch. This approach knits the open-source community together and keeps the PKP team from spreading itself too thin.
In any case, a CMS seems like a natural fit with OJS/OCS to provide a complete website. Some users have interlinked products like Drupal with OJS, which has worked well without any particular concessions to interoperability. We'll definitely be spending some time looking at the best ways to round out our offerings, most likely by streamlining integration with other proven and popular FOSS systems.
Public Knowledge Project Team
Don't miss the First International PKP Scholarly Publishing Conference
July 11 - 13, 2007, Vancouver, BC, Canada