I've not found this characteristic documented. Had I known/understood, much time would have been saved. The events in an Automator calendar within iCal are not passed on to other Macs that are synchronized through .Mac. This is good thing, and to be hoped for, but this functionality had not occurred to me.

I had created iCal plug-ins via Automator, then moved them to my personal calendar. Overnight, they passed through .Mac to my other Macs, where the timed routines failed because the routines weren't meant for those Macs. Returning the Automator events to the Automator calendar, and re-syncing all my Macs, resolved the issue as the events/routines "disappeared" from iCal on the other machines.