Macs, PPC, NeXT... History
O'Reilly posted part 1, and part 2 of an article entitled "Steve Jobs and the History of Cocoa"... which gives a brief overview of Cocoa/Mac OS X's origins. An interesting read, and touches on Star Trek, Apple's attempt at Mac OS on Intel.
Haxor.dk published an interesting overview of the PowerPC processor line... from the 601 to the 8500 designs. (link credit: Peter Perls)