It includes various Java hosting companies people have recommended over the years. While the entry level plans often don't include JBoss (or any app server), they all have more full-featured plans that include that.
I personally pay for a virtual host that lets me install and run whatever I want. I just pay for a certain amount of dedicated ram / disk space and I can run my own linux server.
I pay about $25 for an unmanaged 256M RAM / 10GB space / 300GB bandwidth account at vpslink.com. Just remember to run Xen and not OpenVZ if you want to run Java. I run CentOS and use the free HostInABox / LXAdmin control panel for server management, which is not the best, but it gets the job done.