Sugar is a platform ontop of Fedora Linux that has been designed for the OLPC project. What struck me when I used it for the first time wasy "Wow. This would be amazing if eyegaze dwell worked on this and a nice, configurable OSK was part of the package". The OSK is possible the only thing that isn't is actually using a Tobii device with this. Have Tobii publicly/privately discussed or actually created drivers and a configuration app to run on linux? Sugar would be a far easier environment to run eyegaze than windows - particularly for emergent eyegaze users...children or otherwise.

http://www.sugarlabs.org/