Lubuntu 12.10 ships with Lightdm as the default window manager. It is flexible and fast. It allows you to select alternative greeters and a wide variety of defaults. The Ubuntu wiki has excellent documentation for the configuration. However, the autologin feature was not quite right. I configured it to log into a no-password user account. The user entry box would disappear, but it would not continue into the session until you manually pressed the "login" button.
I located some other people experiencing similar problems, and there is a potentially related bug on file: Bug #902852 “Timed autologin feature not working” : Bugs : “lightdm” package : Ubuntu
After some trial and error, I determined that it was not lightdm causing the problem -- it was the greeter. The default Lubuntu greeter is lightdm-gtk-greeter. It is possible that there was a solution with an alternate configuration (e.g., maybe the autologin user needs a password), and it is possible that a newer version of the greeter would work if I wanted to mess with the repos, and it is possible that any number of lightweight greeters could have done the trick. However, I took a straight line to a solution.
I installed unity-greeter and adjusted the lightdm.conf to use it. The unity-greeter appears to be default in Ubuntu, but Lubuntu chose a lighter greeter. In fact, unity-greeter installed 247 new packages on the system. That seems quite unnecessary, but it was a stable and quick way to address my problem. Given the activity on the bug report above, I'm optimistic that future versions of Lubuntu and lightdm-gtk-greeter will not have this problem.
- sudo apt-get update
- sudo apt-get install unity-greeter
- Edit "/etc/lightdm/lightdm.conf" and update line "greeter-session=unity-greeter"