"This document does not aim to regurgitate Marketing KoolAid, not that there's anything wrong with it™, but is intended primarily as an introduction to Mac OS X for those members of the technical community who are not familiar with it." This is a must read for anyone interested in Mac OS X technology. In a slightly related article see also: Command Line Archival in Mac OS X.
Billy Joel - The Essential Billy Joel - Disc 1 - Captain Jack