We already get property data in the factbox, which is very handy for developing, maintaining, and using a semantic mediawiki. All that remains to be added is information about categories, templates, and forms that are used for the page. Likewise, categories, templates, and forms could also have information about which of those three things go into defining them (like if a template is created by a form, or if a category is contained in a template).
I have been able to manually add these features to this page (user Demo, pass dedauw):
http://www.coincompendium.com/wiki/index.php/File:1989GWWcto.jpg
Wiki developers, maintainers, and users can easily access the categories, templates, and forms that go into creating that page, all in place. In addition, I'm able to query the semantic data to display on the template page which pages are using the template:
http://www.coincompendium.com/wiki/index.php/Template:Image
The nature of these things makes it straightforward to add them manually once, and then use them unlimited numbers of times. However, if the properties "Category", "Template", and "Form" were part of the metadata of each page, they could be displayed in the factbox that already handles other properties.
Also, my factboxes do not show special metadata properties like the "Modification date" property that currently exists - this should be at least optional, if not the default).
See also: https://bugzilla.wikimedia.org/show_bug.cgi?id=13151
Version: unspecified
Severity: enhancement