IMO, Mac OS X is everything that Linux on the desktop wants to be, just that it's on a PPC chipset and it has a price tag.

Think about it. It's a robust and secure operating system that can run many MANY opensource apps in root-less X11, has a UI that is easily understandable by novices and is functional in nature, has a immense collection of various terminal and text editors to support any preference, is frequently updated against security concerns, and is rock-solid stable.

It's just confined to the PPC chipset and costs money...