This is an old revision of the document!
This is the start of the dev: namespace.
These would normally be complete versions of the official core source code; either the base Subversion repositories, or up-to-date mirrors.
Dan Scott has been working on an excellent developer's tutorial, located here: http://evergreen-ils.org/~denials/
Semi-regular developer meetings have been taking place on IRC. See meetings for agendas, minutes.