One of the things that I love about open source is that it's a great way to let innovation and collaboration happen in the absence of lawyers dictating every jot and tittle of an integration. As a case in point, I woke up today to see that someone has integrated Joomla! with Alfresco (and dubbed the result "Joosco").
In a nutshell, Joosco is a front-end for Alfresco, in Joomla!. It works by creating a new entry in a menu in Joomla, called Documents, for example. The users can click on this link to go to a new page where they can browse through spaces and content of the Alfresco Repository. The plugin is used to authenticate users to the Alfresco repository. Alfresco users can now log in to Joomla, and their permissions in Alfresco are used to display only the content they have permission to access.
Alfresco, my company, didn't write that extension. To the best of my knowledge, the core Joomla! team didn't, either. Who did? The community. Why? Because they had that need and so filled it. What enabled it? Open source.
Open source lets code speak for itself. I'm a big fan of Joomla! but don't have the expertise to write this sort of integration. The community does. So it did. Because it can. That's open source.