Could somebody tell me? From the README in /usr/doc:
What is ConsoleKit?
ConsoleKit is a framework for defining and tracking users, login
sessions, and seats.
What is a seat?
A seat is a collection of sessions and a set of hardware (usually at
least a keyboard and mouse). Only one session may be active on a
seat at a time.
What is a session?
A session is a collection of all processes that originate from a single
common ancestor and retain knowledge of a secret. As an implementation
detail, this secret may be stored in the process environment by the
login manager under the name XDG_SESSION_COOKIE.
Discussion takes place on the HAL list.
Honestly, I have not the least idea what this README is speaking about.