Well, Zingersoft answered me with its latest update, officially released a few days ago. In this update is multitasking support, allowing you to keep connections open in the background for up to ten minutes on compatible devices. And because there's now multitasking capability, the update allows one to setup port forwarding tunnels.
If you don't have access to a VPN server to pass through firewalls in order to gain access certain systems, the port forwarding feature of iSSH is a godsend. As for the ten minute timeout, that's only to be expected. Though, I'm assuming all one has to do to reset the timeout counter is occasionally switch back to iSSH and back out again.
iSSH is a universal iPhone and iPad app, currently available for US$9.99 in the app store.