User Feedback :: Keep applications running on terminal exit?

On older DSL distributions, I've noticed that applications will still keep running after a terminal session is closed or exited.  How is this accomplished?

Typically, when exiting a session a HUP (hangup) signal is sent to all child processes and they shutdown.  But Damnsmall Linux doesn't behave this way; process still stay running.  
How is this being accomplished?

I'd like to reproduce this.
It is definitely not using 'screen'.


original here.