Yes, it is an experimental thing offered by the chat client service we use. Doesn't yet give a list of users in the chatroom and is only updated every 20 minutes, but it's a start.
There are also some charts they generate showing chatroom usage:
... you can see links to these charts down the bottom of the main forum page.
One day I'll find some time to write my own egg-drop bot for the chatroom which can extract more accurate details about how many people are in the room and what their chat nicks are and such.