I've been looking over this, and can create a rough mockup of how the portals work within mediawiki. There are several 'issues' that I can't see a work around.
First, there is no way of linking back to the edit page for an article. Atm, the BBCode won't add it to the end (naturally) and if you link using the URL BBCode, then it creates an 'outside' link. Is there a way of working around this limitation? Could a change be included to VW?
Second, the ability to transclude articles is important for this to work. Atm, each 'article' has to be manually created. Would it not be possible to include a transclusion of a regular article or section of it (if it had appropriate markup in the BBCode) into another page?
Third, there are a number of little additional features that they have, such as a random selection of articles based on set criteria (I think it's a list within an article), a category list showing an expandable tree from the parent categories, etc. Could options like this be designed in some way within a sort of 'advanced' BBCode manager? Such a BBCode manager would need to be able to benefit from the template system, and be able to process data much as the parser extensions do atm.
Are any or all of these something VW could develop and include?