Wow. Just three months with my iPhone tied to an Exchange Server and I forget how to use a manual calendar. I've started missing every event that I don't RSVP to in the form of a calender invite...
I've got it worse--I made a calendar alert on my iPhone to download the free Crossover Office yesterday, as soon as I got home--then forgot, because I'd added it to another calendar entry. There's probably a business opportunity for a service to aggregate your notes/appointments from different sources, sort them, and output them automatically to a format of choice with reminders at varying levels of assurance.