Following up on your comment on the Technical Update, I made some changes and restore the Facebook Like Box on Template:Maintop with the updated code from FB that uses div tags. The Help page still needs to be updated with this info, I apologize that it has not been done yet. You can see some of the parameters available for this at https://developers.facebook.com/docs/plugins/like-box-for-pages if you want to try some different things. Let me know if you have any questions!
It looks like the release last week might have caused some trouble with all of the Facebook plugins on Wikia. I can't get anything to show right now, but we're looking into it. I will let you know when it's fixed!