At Apogee we love Open Source systems. Quite often we use libraries (like jQuery) or whole systems (like Horde) in cases where we would be just re-inventing the wheel and the open source solution more than covers our needs.
Open source content management systems are an easy and quick way to get a web site on the air. But at times as they are trying to provide something for everyone they end up with overcrowded interfaces with a million features that are not used.
We were recently asked to convert one such site to the Essence platform. With a final implementation time of a few days (from database conversion to content clearing up) we provided a site with the same functionality as before but with a much more concrete administration interface, removing the need for a specialized administrator to manage the content.