I've been looking at some different open-source systems, trying to decide which one I might use.
Mambo/Joomla
Pretty neat and tidy admin interface and the templating system is fairly easy. Tends to be based more toward news entries rather than longer static content. As with xoops, it has a rigid section/category system which, for a simple website, just gets in the way.
Typo3
Very comprehensive system with great handling of static content but maybe too hard to use. I was unable to find any decent selection of pre-made templates so I would have to look at creating a template from scratch - maybe that's not too hard(?).
xoops
Similar to Mambo in the way it leans toward News layouts. Admin interface wasn't as intuitive.