At this time, the X.org Foundation is not making binary releases; this will likely change in the future as our tinderbox system reaches its full potential.
However, people are already packaging the distribution for release in many of the common distributions (e.g., Fedora Core, SuSE Linux, Debian), and you may wish to work with those distributors on their packaged binaries.
In the meanwhile, we recommend building X from source and doing an install on top of your running X installation *after* having carefully backed up /usr/X11R6 to allow restoration in case of some unanticipated problems. See the file INSTALL.TXT in the root of the source distribution for build and install details.