Well, new-ish extension: it was released last week, but version 0.2 was just
released, and now it appears to be fairly stable. Approved Revs is meant to
be a lightweight alternative to FlaggedRevs, for small- to medium-scale
wikis. It lets administrators mark a single revision of a page as approved,
and the approved revision is what's shown to users, even when the page is
transcluded.
You can read more, and download the extension, here:
http://www.mediawiki.org/wiki/Extension:Approved_Revs
-Yaron