The problem is that the network has not been started when the XFinit script is run.
Take a look at /sbin/init - this seems to be the main init script. Specifically look for the three lines starting with "# 95 mlinit-0.2". This is where the network is started and it is after the /usr/sbin/init script is called which in turn calls the /usr/X11R6/init script (which is actually a link to /tmp/config/XFinit).
I fixed the XFinit mount problem by editing the /sbin/init file (in the build kit - not on the IA1 running Midori) and moving the network start and portmap lines directly before the call to /usr/sbin/init. Once you have made the change in the buildkit, simply run the "build" script. I am using RH 6.2, but it should work on other Linux distros.
I'm not sure why they chose to start the network after X, but my mod seems to work correctly and allows me to put my mount calls in XFinit and freeze the config without rebuilding the CF image.