I know this question has been tossed around by many developers and designers. I just got finished with my companies intranet site using joomla 1.5 with a custom bulit template and modifying almost everything in joomla. It got me thinking if I should be using an enterprise CMS instead of an free open source CMS. I almost went with wordpress, but the company wanted joomla for there site. It was a great for me to jump into another CMS and learn, but is there a better CMS out there that meant for intranet or does it really matter at all?
Try OpenAtrium, its free.