Sometimes lightdm comes up fine. Other times it appears to fail. x-0.log shows it tried to load 'nv' (rather than 'nvidia' which is what actually exists). When I then log into console and 'start lightdm', it comes up fine (on :1).
I've not had it come up ok today, so I don't know if, when it comes up fine, it starts on :0. No idea if the lightdm.conf needs a change to 'start on'clause, or if this is just a case of a bad shipped config file (for module 'nv').
DistroRelease: Ubuntu 12.04
Package: lightdm 1.1.9-0ubuntu1
ProcVersionSignature: Ubuntu 3.2.0-20.33-generic 3.2.12
Uname: Linux 3.2.0-20-generic x86_64
Date: Fri Mar 30 13:40:27 2012
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Alpha amd64 (20120323)
UpgradeStatus: No upgrade log present (probably fresh install)