If Moodle is anything close to Desire2Learn (which I saw and used at UW Oshkosh), it will have slowly crawled into the CMS space. The only limitation might be that you have to host content inside a "class" or equivalent content object. I saw people jump through hoops with D2L, creating fake classes just to post something, and having to add lots of people to that fake class' roster so they could see that content. If that's the case with Moodle, then there is room for Plone. Otherwise, the integration would make sense only if there were something else Plone can do that Moodle can't, like workflow, Dexterity, an add-on that does something that Moodle (or its add-ons) can't.