No mention of this during the keynote, but Apple has also released it’s own packaged version of X11.
X11 for Mac OS X Public Beta is an implementation of the X Window System that makes it possible to run X11-based applications in Mac OS X. Based on the de facto standard for X11 the open source XFree86 project X11 for Mac OS X Public Beta is compatible, fast, and fully integrated with Mac OS X. It includes the full X11R6.6 technology including an X11 window server, Quartz window manager, libraries, and basic utilities such as xterm.