So the fix for the X problem in 5.5 narrowly missed the 5.6 release. It is part of the 5.6 source, but it's not in the binary. I assume the build for the Z starts earlier than other platforms given that it's built natively on a Zaurus and must take quite a bit longer.
To get the fix, do your upgrade/install to 5.6
Grab the xenocara.tar.gz from your local mirror.
Cd to /usr
Extract the tarball.
Cd to /usr/xenocara/lib/libpciaccess
Build with:
make -f Makefile.bsd-wrapper obj
make -f Makefile.bsd-wrapper build
That will do the install as well. Fire up X and you're good to go.
Don't worry, the build for just this library doesn't take very long.
Tim.