I have draft ideas, and probably naive ones.
First one was to implement in a beta wiki SMW and download the dump of it.source, to see how it is working.
My idea was to create a template with DC fields, so that the template can accept metadata the old wiki way, and all the Semantics can be embedded in the template itself.
Moreover, there could be a form like Commons has for file uploads: DC has optional fields and also repetitive ones (you can have them as many as you need).
This could be very important because some metadata needs to be properly addressed. If you think about the field "Year", you don't know if it is the year of creation or publishing, and there many other different possibilities.
I don't want to import the complexity of MARC (
http://en.wikipedia.org/wiki/MARC_standards) in Wikisource, just more reliability and authority.
Moreover, I just don't get what the OAIrepository extension (implemented everywhere) is doing.
I would like to understand better how it can be used.
In the Italian Wikisource we have developed complicated procedures to harvest data via transclusion (the Labeled transclusion extension is extremely powerful).
Unfortunately, with section stransclusion you *always* need to explicitly write in wikitext the section tags (<section>), which "spoils" and complicate the text for users. I believe the best way is to hide complexity within software extension or templates, and maybe develop forms for guide users.