He also flubbed using ssh-agent. Usually it is run from the login script once. You then do a ssh-add to add your identity to it. Once that is done you don't need to enter your password for that session anymore. You can even allow ssh on other systems to access your agent so you can ssh to another machine, ssh from that machine to a 3rd which will use your agent for the key info.

Never leave your key without a passphrase!

A good series of articles on ssh bt Brian Hatch can be found here - http://www.hackinglinuxexposed.com/articles/20021211.html