Hello,
The discussion so far has been about biographical data on Wikipedia
and licensing data on Commons, but other projects have their own needs
for it.
Wikisource, especially, is in desperate need of metadata. We have some
140,000 pages on the English wiki alone that represent poems,
chapters, tables of contents, and so forth. These are essentially
disorganized: we have human-usable templates and categories, but
there's really no good way to find works besides searching their
titles.
A few years ago we combined our metadata templates into two standard
templates, {{header}} (for works) and {{author}} (for authors). Every
single page already provides metadata to these templates, so
implementing a metadata format for machine use is trivial once it is
available on MediaWiki. We *really* want this; it would allow us to
index our jumbled pile of works and authors in all sorts of very
useful and interesting ways. Just a few example are author search and
autocompletion (we currently list works manually), finding works by
genre and year and subject and so forth, searching work descriptions,
and distinguishing works from subpages.
Both formats have their own advantages and disadvantages. Microdata's
simplicity is a significant advantage, but RDFa's built-in validation
is also nice. Whichever format we choose, we'll make it all work
behind the scenes in the murky depths of our templates. But it would
be nice if you'd include creative works, authors, navigation, and
indexes in the equation. There's more here than biographies and image
licenses. :)
--
Yours cordially,
Jesse Plamondon-Willard