I downloaded Plone (with Zope 2.7.3 no less). It got itself installed and running with zero cleverness on my part. It was only when I started playing with it that I became confused. An example that sums up my experience nicely: I was able to install an iCal-compatible calendar product and access it through WebDAV from iCal, I was not able to work out how to add an event to the calendar however!

Edit: Oh, got it now. This thing is a bit mad though.