Xdmx

This software will let you configure several machines running X as one large display.

Project Home Page -- http://dmx.sourceforge.net/

setup machines

install xdmx

sudo apt-get install xdmx xdmx-tools

You need to make all the display accessable via TCP, edit /etc/gdm/gdm.conf and turn off "DisallowTCP=false"

sudo vi /etc/gdm/gdm.conf

You may want to generate a /etc/0.hosts file.  This will allow the listed computers (clients in Xspeak) to access this server.

sudo vi /etc/0.hosts

an example 0.hosts file

root@ubuntu3:~# cat /etc/1.hosts 
10.2.0.160
10.2.0.192
10.2.0.195
10.2.0.75
10.2.0.76
10.2.0.167

Make all Xservers the same, disable any features that aren't in all Xservers.

Docs installed into /usr/share/doc/xdmx and /usr/share/doc/xdmx-tools