Hi Tim,
Anyone familiar with Confluence will know about the
concept of "spaces"
which are essentially logical containers for different topics, keeping
groups of pages confined to their topic group.
I wonder if anyone knew if MediaWiki has any plugins
to emulate such
behaviour?
You should come a long way using categories and/or custom name spaces.
You might also have a look at Semantic Wiki for content control within a page.
hth
Frank