After an initial reference implementation in the English Wikipedia and some bottom-up implementations in a number of projects, the licensing update to the Creative Commons Attribution/Share-Alike License as the primary text license, with GFDL as a secondary license with limitations, has now been implemented in all previously GFDL-licensed Wikimedia Foundation projects.
Wiki communities can now customize these texts further in accordance with the implementation guidelines issued by the Wikimedia Foundation at:
http://meta.wikimedia.org/wiki/Licensing_update/Implementation
Importantly, this allows Wikimedia wiki communities to create their own copy of the terms of use, with specific limitations on or guidelines for attribution of externally imported CC-BY-SA content, more detailed explanations for re-users, etc. The implementation guidelines do allow significant flexibility, but we're hoping to ensure baseline consistency across projects and languages, so please do not deviate significantly from the guidelines. (If you feel the guidelines are flawed, feel free to comment on the talk page on meta.)
If the messages have not been translated into your language yet, it is appreciated to do this work through <translatewiki.net> so that it doesn't have to be redundantly done for each Wikimedia project in that language. As translatewiki.net translators know, localization changes from there are rolled out regularly alongside normal code updates. Thanks to our good friends there for helping with the process so far, and thanks to all the translators.
The relevant user interface texts are MediaWiki system messages and can be viewed and edited through the MediaWiki: namespace. They are:
[[MediaWiki:Wikimedia-copyright]] for the site footer [[MediaWiki:Wikimedia-copyrightwarning]] for the editing page, above the save/preview buttons [[MediaWiki:Wikimedia-editpage-tos-summary]] for the editing page, below the save/preview buttons.
For the more technical users, these changes were introduced to MediaWiki in the following code revision: http://www.mediawiki.org/wiki/Special:Code/MediaWiki/52361. They live in the WikimediaMessages extension, which is only used by Wikimedia Foundation wikis. These messages override standard system messages, [[MediaWiki:Copyright]] and [[MediaWiki:Copyrightwarning]]. [[MediaWiki:Edittools]] has sometimes been used to move this type of licensing information below the buttons/summary; the newly introduced [[MediaWiki:Wikimedia-editpage-tos-summary]] is meant to reflect this need while allowing us to consistently update/review these messages.
Finally, a note on trademark recognition. Some projects have a little trademark notice in the footers, others don't. This notice isn't required (but helpful); we're working on standardized trademark usage guidelines, and we'll probably add a link to the site footer to these once they're finalized.
I'll be checking the wikis, and particularly [[m:Talk:Licensing update]] and [[m:Talk:Licensing update/Implementation]] for comments, but please let me know if there are any immediate issues.
Thanks, Erik