In October of 2006, I presented to a Mac Users group a presentation on Mac OS X, and the relationship that it has with UNIX. These are some helpful resources that I used to create my presentation.

UNIXKeynote - Presented Oct 24th.

Speaking UNIX - A collection of papers from IBM about the UNIX operating environment.

Mac OS X Internals - A supplement to the Mac OS X Internals: A Systems Approach. This PDF file is basically a book in itself! It goes into great depth about the history of operating systems, and how Apple fits into the “Big Picture” of OS development.