Thanks for the tip.
I have an iMac whose built in LCD has started the "lines of death" spiral, so I know that eventually it will be totally useless. I have an external monitor, running in mirror mode, that keeps it from being tossed in the trash.
Having an Automator script to ensure that mirror mode is always put in place on startup would provide some security. I'm hoping that the upgrade to Snow Leopard, which means running without scripts and requiring that the internal screen be functional, won't mean the end of system software upgrades for the iMac.