Both the Wikia software and the Wikimedia Foundation software are open source and this allows for the use of the Wikia software by the Wikimedia Foundation.
Tim's question is timely as well as opportune: Brion is back and he is tasked with revamping the parser and implementing WYSIWYG for MediaWiki. It would be stupid to develop something new when there is already something that is already adequate.
There are important advantages:
- the software is already in production at Wikia
- the software is being localised at translatewiki.net
- this is experience how WYSIWYG affects MediaWiki newbies and oldies alike