I'm the community coordinator for the open source team at Open edX.

We're in the process of centralizing our documentation and dispersed information. In the mean time, you can check out:
-Project home http://code.edx.org
-Github wiki https://github.com/edx/edx-platform/wiki
-Confluence https://openedx.atlassian.net/wiki/dashboard.action
-mailing list https://groups.google.com/forum/#!forum/edx-code
-edX.org, a site where edX hosts courses http://edx.org