Wikisource is powered by a MediaWiki extension which allows page images to be displayed beside the wiki editing form. This extension also handles editorial workflow by allowing pages, chapters, and books to be marked as unedited, partially edited, in need of review, or finished. It's a fine system, and while the policy of the English language Wikisource community prevents it from being used for manuscript transcription, there are active manuscript projects using the software in other communities.
Yesterday, Mark Hershberger wrote this in a comment: For what its worth the extension used by WikiSource, ProofreadPage, now needs a maintainer. I posted about this here: http://thread.gmane.org/gmane.
While I'm sorry to hear it, this is an excellent opportunity for someone with Mediawiki skills to do some real good.