unknown log entry

Recently installed 'logwatch'. On examining the output, the following entries are regularly found in the Connections section:

lightdm: pam_ck_connector(lightdm:session): nox11 mode, ignoring PAM_TTY :0: 4 Times(s)
lightdm: pam_ck_connector(lightdm:session): nox11 mode, ignoring PAM_TTY :1: 2 Times(s)
lightdm: pam_ck_connector(lightdm:session): process already registered with ConsoleKit: 1 Times(s)
lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "<my user name>": 3 Times(s)
lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "<my other user login name>": 2 Times(s)

What is lightdm all about?

The system is Ubuntu 11.10, and is fully updated. I have two user logins configured, one standard and the other administrator.

I also have an Ubuntu 11.04 system on my machine which does not havve any 'lightdm' entries in the logwatch output.