Additional resources
Review: Leopard Server: The people's UNIX
Mac OS X v10.5 is true UNIX on the inside, novice admin friendly on the outside, and born for collaboration, with turnkey-simple blog, wiki, IM, and calendar services
A developer's-eye view of Leopard, part I
Xray and Core Animation stand out among Apple's immense bag of new Leopard tricks
A developer's-eye view of Leopard, part II
Leopard's Xcode3.0 integrated development environment and Objective-C 2.0 language help define the Mac platform
A developer's-eye view of Leopard, part III
Cocoa and other sweet object-oriented frameworks magically make all Mac apps part of an integrated suite
A developer's-eye view of Leopard, part IV
64-bit Darwin, Dashcode, Time Machine, and Ruby on Rails call on developers to trade out established skills for new ones
Tom Yager: Enterprise Mac