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