There may be other unforeseen breakage primarily in the handbook portion of the wiki.
The Table Of Contents section of each "PC-BSD® Users Handbook" page may be the best workaround.
PC-BSD Thin Client Server Documentation
This document provides documentation and help for system administrators who wish to use a PC-BSD system as a Thin Client Server.
Converting a PC-BSD system into a working thin-client server is relatively simple. First, you will need an install of PC-BSD 7.x or higher, with dual network cards. One NIC should be connected to the outside world, while the other should be connected to a private LAN for the thin-clients to PXE boot from.
Once your system has the NICs setup properly, go ahead and grab the Thin Client Server PBI from here PBIDir
To install, simply double-click the PBI, or execute it "% ./ThinClient*.pbi"
During the installation, the only question asked will be to identify which NIC you want to run DHCPD on. Select the NIC which is connected to your private network for PXE booting. After the install has finished, simply reboot the server for the changes to take effect. That's it! Any systems which are PXE capable should now boot up, and connect to the PC-BSD desktop via remote XDMCP.
While the initial setup of the Thin Client Server is relatively simple, you may wish to further customize the system after installation. This can be done by editing several of the configuration files used for operation.
This file is used to control the dhcpd and PXE boot configuration. You may change the IP configuration of dhcpd or increase the range of addresses and more in this file. More information about this may be found here: 
WARNING: Changing this file is risky, and could break your PXE setup. If you change the network addresses, you may also need to modify /etc/exports, /etc/hosts.allow and others to reflect your changes for NFS mounting.
This file is used by KDM to adjust the login manager. Most of the variables are well documented, and you should take a look at them if you want to adjust any aspect of the X login screen that the client is presented with.
Q. Where is the client's boot environment stored?
A. The clients boot environment is located in /home/pxeboot. This is mounted read-only during the PXE boot process to allow the client to bootup, and then bring up an XDCMP connection to the server.
Having trouble or want to help us with the Thin Client Server PBI? Please feel free to contact us on the PBI Developers Mailing List