I don't know if it shows people after they actually bother to log out, but it might. The fact is that the list just has no connection to reality. I don't know if actually reading the Session table would be any better either.
Nancy
Injustice anywhere is a threat to justice everywhere. -- Dr. Martin L. King, Jr.
From: steeph How accurate is the block in core? Doesn't it still show users a few minutes after they logged out. It's not a problem to create a view with the same functionality.