The beautiful Google Calendar has a better way of managing reminders. Now you can set reminders for individual events, even if they aren't on your primary calendar.
For each calendar, you can set what notifications you want: pop-up window inside Google Calendar, email, SMS, or a combination of all of these. Just click on the arrow next to each calendar from the left sidebar and select "Notifications", then add up to 5 event reminders. In order to receive SMS messages, you need verify your phone number first.
But if you have special events that require a different kind of reminder, you can set it when you create an event in the Options section.