In three months the guys of canonical are releasing the next Ubuntu version. As they did with the 6.06, the 8.04 is a LTS (Long Term Support) version. That ensures three years of support (updates, security fixes, etc), so these versions are ideal for sites intended to be working for a very long period of time with a minimal maintenance (i.e. no intentions to do major version upgrades but only keeping up to date the original version).
There are several changes that affect to the current multiseat configuration. The goal is just the same as it was in our fist multiseat configuration (using Ubuntu 6.06): To obtain two seats using just one graphic card with two video outputs.
The Ubuntu 8.04 release includes xorg 7.3 with some important changes compared to previous versions. The main advantage of that version is that the xserver-xephyr package includes support for evdev input events. We finally can obtain a full multiseat computer just doing some modifications in configuration files, and with no need of external patches. That eases the setup of the system as well as it avoids problems in the process of package updating.
Another relevant change is the use of xrandr instead of xinerama to manage the multiple outputs of a video card. At the begining that was a problem until we found a way to obtain the same as we did on the previous version: Showing a xephyr session on every screen.
We have been doing several tests with Ubuntu 8.04 alfa 2 and alfa 3. The result is a working prototype but we are still having some issues to fix. The fact of working with alfa and prerelease versions means to deal with additional problems, but we are confident in obtaining an easy to follow step by step tutorial to create a two seat computer when the final 8.04 version will be released.