I was unable to view a Google calender that was shared with me on my iPhone. I came across the following link where I was able to simply check the shared calender to have it display on my iPhone. I have no idea how to navigate to the link. It sure is not obvious.

www.google.com/calendar/iphoneselect

Furthermore, you can configure notifications for the shared calender after you validate your phone (not iPhone specific now), which you can get to from Google Calender, Settings, and Mobile Setup.

Once your phone has been validated, you can configure your notifications to send you email, pop-ups, or SMS notifications.

Now, I am curious to see how it works with the shared calender on my Galaxy Tab, since I did not have notifications setup for the shared calender. I hope it does not need to configured as a mobile device too, because I did not see an option to verify a second mobile device.

Update: Ok. I got this figured out now. Notifications for shared calenders are not propagated to any device. You can set up notifications on my iPhone and my Galaxy Tab or you can manage the notifications from your Google Calender account. The later would be the best way to deal with more that one device. You just set up the reminders, and choose a number of options, including email, SMS or pop-up. You can even set up default notifications for a calender shared to you in the calender settings. However, this does not apply to entries already shared to you.