Mac OS X, Intel Style
When it comes to Intel Macs, the ideal situation of portability no longer holds true. Apple actually ships Intel Macs with an Intel-native version of Mac OS X and issues separate Mac OS X updates for Intel Macs. You can see evidence by looking at the build numbers between Mac OS X releases on Intel and Power PC Macs. Although two Macs might be running Mac OS X 10.4.6 with the latest security updates, the build numbers for the OS X release will look like 8I1119 and 81127, respectively.
This might come as a surprise because Apple has indicated that all the software that comes bundled with a new Mac is universal (that is, it contains the code needed to run natively on both Power PC and Intel Macs). Although it is true for almost all applications and utilities that ship with Mac OS X (Safari, TextEdit, iTunes, and the other iLife and iWork applications), it is not true of the entire operating system. There are elements of Mac OS X that are specific to Intel or Power PC hardware. Most of these files appear to be device drivers and kernel extensions.
This throws a wrench into the idea of using a single Mac OS X image as a deployment option in a network that contains both Intel and Power PC Macs. In fact, at this time, Apple has officially stated that it does not support the creation of a universal Mac OS X version by end users. However, Apple has also indicated that it does plan to eventually reintegrate both Intel and Power PC variations of the operating system into a single release (though unconfirmed, many expect that this will happen in Mac OS X 10.5, a.k.a. Leopard). However, this is not the only difference that exists between Intel and Power PC Macs that affect the capability to create a universal image that can be used for deployment to both types of machines.