Virtualization with FreeBSD Jails
Subject:   ezjail port...
Date:   2006-03-10 08:32:38
If you're going to be setting up a lot of jails on 6.0 , take a look at ezjail.

You set up a master jail, then "clone" off of that, mostly through nullfs mounting and links.

I haven't used it, but my understanding is that new jails take up about 6mb of disk space before any customizations.