Keyboard shortcut activates screensaver and locks session.
Salute allows you to start your screen saver using a keyboard shortcut (ctrl-command-delete) instead of having to use hot corners. If you turn on the option of requiring a password when exiting from the screen saver, this allows you to lock your session with a keyboard shortcut.
You can enable screen saver locking by going to System Preferences ->Security, and selecting "Require password to wake this computer from sleep or screen saver".
Salute also allows you to launch Terminal or Activity Monitor. This is handy if the Finder is not responding, can't be re-launched, and you need to launch get back into the system for maintenance.
You can also select if you want to go to the Login Window instead of the Screen Saver. This does not log you out, and does not require that you have Fast User Switching turned on.