Wikidata: Wikipedia Free Knowledge Base

Wikidata is a free knowledge base that can be read and edited by humans and machines alike. It centralizes access to and management of structured data, such as interwiki references and statistical information. Wikidata contains data in all languages for which there are Wikimedia projects.

Key features of Wikidata:

• New: Wikidata is a first new project for the Wikimedia Foundation since 2006.
• Free. The data in Wikidata is published under a free Creative Commons license.
• Multilingual. Editing, consuming, browsing, and reusing the data is fully multilingual. Data entered in any language will immediately be available in all other languages;
• Structured. Collects data in a structured form. This will allow easy reuse of that data by Wikimedia projects and third parties, and will enable computers to easily process and "understand" it.

Current aim of Wikidata is to collect the language links for Wikipedia articles. You can go to a random page on Wikidata and check it, and add a short label, description and aliases, and you can do it in English or another language.

If you are brave enough, here is item listing all 286 editions of Wikipedia's Main Page.

See also Wikipedia is now drawing facts from the Wikidata repository, and so can you, GigaOm, Apr 26, 2013.