Part of the problem is the term portal is used about a million different ways. Some people insist on customization -- being able to pick and choose from broad categories of information (sports, entertainment, etc.). Others go further and talk about personalization -- being able to integrate calendar, e-mail, and things that are unique to you. Some people talk about portals as simply sites that pull together lots of relevant information on a particular subject that often come from different sources (with or without the customized part).
So it kinda depends on how you define the term. Mambo certain works for the later, broader concept. And it _can_ work with a lot of tweaking in the customized sense. (modify something like user extended and call custom modules based on it would be one approach)
Once content is being dished up by a database, there's no reason you couldn't build in some features that make it easy to do things like that... But I wouldn't want Mambo looking like MyYahoo! either.
Content management is and should remain the core and the focus. That's what drew me to Mambo instead of the Nukes -- which seemed too much like community portals with CMS tacked on.
But having both some community and some customization features and enhancements wouldn't be a bad thing, IMHO. A CMS with community and portal tacked on sounds better.
