(In reply to comment #9)
> I recognize this problem from some time ago. Have you tried applying the ubuntu
> patches to see if the problem goes away? (apt-get source
> xserver-xorg-input-synaptics, then look in debian/patches.) There might even be
> additional patches available at ubuntuforums for this. I am particularly
> thinking of the patches that disable movement when more than one finger is or
> recently was in contact with the touchpad.
I wrote the patches in Ubuntu (I'm a Canonical employee) but if you have links to additional patches I would be glad to have a look at them.