Google Calendar has expanded its notification options to include individual events—including those not on your primary calendar. Here's the scoop according to Google Operating System:
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.
Nice! You can pluck events from family, co-worker and public calendars and set up notifications for just the ones you want. Unfortunately, this new capability seems to be on hold temporarily, as it doesn't appear on my calendar, and several commenters to the above-referenced post have mentioned that it appeared and then disappeared. But it's also mentioned on The Official Google Blog, so it will undoubtedly return soon. (If you have updates, share 'em in the comments.)