[michael_miller]

This is a very rational decision for Apple to make. 99% of their customers don't even know what X11 is, yet most of them will be downloading Mountain Lion from the Mac App Store. Not bundling X11 saves most users 70MB of unnecessary download.

[jwbaker]

It's been some time since Apple shipped the X11 package by default. You've had to download it yourself. They're not saving anything by removing it from people's computers