Due to recent changes in United States Federal Law, specifically the Children's Online Privacy Protection Act (COPPA), anonymous editing has been disabled on the Pirates of the Caribbean Wiki. You can read the full story on the Staff Blog here, but below is a brief summary.
COPPA was passed to protect the privacy of children, defined as any person who is under the age of 13. This legislation prevents companies from collecting various bits of "information" from children. The July 1st update expanded this "information" to include IP addresses. The Media Wiki software, which is what wikis are mostly made of, use IP addresses to monitor the anonymous editing. Now, because there isn't an easy way to monitor the age of anonymous editors, wikis which are directed at children have had anonymous editing disabled.
They can still view all the articles, but must log in to be able to comment or edit. If you have any questions, please ask, and I'll try my best to answer. :)