5
Plone is a CMS in the classic sense of the term. You have a website, you have text and images on the pages of your website. You don't want to have to edit the web pages directly in order to update content, plus you want to be able to push ownership and editing responsibilities to other people besides the technical webmaster.
So you user a Content Management System to edit and update the content on the web pages without actually editing the web pages. A good CMS has workflow controls and strong role-based permissions for different users (can edit, can publish, can add new content, etc). And a good one will differentiate between different types of content (text, images, certain kinds of text (intros, body text, tables, etc), and even let you create new types to suit your needs.
A good CMS also has versioning control, so you can go back in time and see what a page looked like last week or last month because all versions of all content are stored, along with the identity of the user who made the change.
XOOPS has none of that. But WF-Sections, or another module, could be built that would give people the ability to have true CMS-like features in XOOPS.
Unlike Plone, XOOPS is a plug-in driven portal framework. Lately people have been pushing the term CMS to include such things as XOOPS, but a couple years ago, you never would have heard that use of the term.
XOOPS is good at giving you a way to bring different users together into groups, and providing the users with different ways of interacting with each other and with content (ie: through modules).
Plone is really bad at that. Plone doesn't even have the ability to put users into groups the same way XOOPS does. If all your users are just sitting in "registered users" or you only care about anonymous users, then the lack of groups support may not matter to you. But for anyone concerned about certain groups having access to certain stuff, and certain other groups having access to certain other stuff, Plone can't do it.
The two systems are really quite different, and each is very good at what it was designed to do.
Personally, I would like to see a module in XOOPS that let you manage content in a separate website, rather than controlling the look and content of pages inside XOOPS.
We have clients who use XOOPS for their "private" intranet style sites, and who also have public sites for which they need CMS features. Why not continue to leverage the XOOPS portal they have invested in, and turn it into, among other things, a control panel for managing their public website's content?
Give it a year or so, maybe we'll release such a module ourselves if there's enough interest on the part of clients.
--Julian