I have to confess that I'm still very unsure of what the label "Enterprise" means, and I become even less sure when MediaWiki is used referred in an Enterprise context.
I thought of it as "use internally in a company", as part of one's intranet.
(My company has a few such internal wikis, and one externally-facing wiki which is basically used as a documentation site for our API but is only writable by particular staff.)
We too use Mediawiki for our Intranet. It consists of a installation of Mediawiki, Redmine, and a few php scripts to make everything work together nicely.