In this sense they are complementary, not competitive.
This is no big surprise. The first release of aD's content
management system was as a separate product, not part of the ACS at
all. CM can be done as a box on the side, so to speak, though
integration has its benefits.
And aD's content management system has been integrated into ACS
4.1, so our OpenACS 4.1 effort will include porting over aD's content
management system (I've already got a volunteer lined up to help out).
At that point, the situation will be that MMbase is a content
management system, while OpenACS 4.1 will be a suite of tools that
include a content management system.
While that appears a clear victory for OpenACS 4.1, let me hasten to
add that aD's content management system is relatively new and the UI,
in particular, could use a little (ahem) work in the opinion of a few
of us, at least, who've looked at it. MMBase appears to be more mature
and they're focused entirely on the CM problem. They appear to have
paid considerable attention to things like making sure it works well
with editors used by user types (as opposed to geek types). My guess
is that they've made it relatively easy to set up solutions for simple
CM problems. So I'd expect them to be strong in areas where the CMS is
(and of course OpenACS CMS is still vaporware, it only exists in the
aD Oracle form at the moment, we won't have it ported over for a
couple of months most likely).
Hey Don, the UI needs work? That sounds like something I could actually help out with! I'd love to take a peek at it and lend a hand where I can. Let me know!