Trisquel devs should know about this LightDM config
Seeing that Ubuntu is moving to LightDM with 11.10 and above, I'm assuming that Trisquel will as well since it is lightweight and customizable. I came across this link today about customizing the background wallpaper and I think its good that the devs know about this for a future release because it is sexy as hell:
http://www.omgubuntu.co.uk/2011/09/tool-change-lightdm-wallpaper-ubuntu-11-10/
Hmm it seems someone has also put together a GUI: http://www.webupd8.org/2011/10/simple-lightdm-manager-change-lightdm.html