After I updated Ubuntu 11.10, LightDM won't show the Unity entry anymore. What can I do, to get the Unity (3D) entry back? NV drivers are fully working. I installed Gnome 3 weeks before.
I seem to remember reading that installing Gnome 3 breaks Unity. It was the case in 11.04 and I think still is with 11.10. Re-installing unity and unity-core may bring Unity 3d back although some of the Gnome 3 pieces you installed may also need to be removed.