We are building our code reference using a combination of wp-parser for the code reference, and a GitHub repo for tutorials and code examples, based off of how jQuery does it. We are building a grunt process to automate the upload to WordPress. In WordPress we use hierarchal content types that are extracted from the GitHub repository and add them to the generated posts. Our theme handles display, tying in the content from our code library repo with what is generated by wp-parser. WordPress is never used for the generation, generated html is uploaded through xml-rpc.
We like this solution because community contributions are managed in GitHub, which has a good web interface that's easy to learn. Also, because we have control pull requests, we have control over what makes it into the final site. This will give us a quality control element that doesn't exist with the free-for-all nature of using a wiki.