Aside from the server change, this release is almost the same as the 2.4.0_beta1 release (meaning all the client side updates are still present). The only change outside the server is for libpng. libpng has been updated to address a security vulnerability (another reason I want to get out another stable release). See the draft release notes for full details:
http://xquartz.macosforge.org/trac/wiki/X112.3.3
The dmg for the release is here:
http://static.macosforge.org/xquartz/downloads/X11-2.3.3_beta1.dmg