Extension:PerPageLicense

The PerPageLicense extension enables license footer variables (viz. $wgRightsIcon, $wgRightsUrl, and $wgRightsText) to be set on a per-namespace or per-page basis.

Configuration
Change these settings to your liking, making sure that you include them in LocalSettings.php after the require_once line installing the extension.

As an example, you might put:

This would license everything in mainspace as Creative Commons Zero.

Usage
Edit MediaWiki:License-templates on your wiki. Add templates and their associated licenses. Put each on a separate line. E.g.: Now any page with the template will show the license footers for CC-by-SA. Note that in the event of a conflict between per-namespace and per-page licensing, the per-page licensing prevails.
 * Wikipedia text || cc-by-sa