Turn off alerts in iCal
So far, I’m liking the new Reminders app on my iPhone. I wasn't liking the little windows appearing on my Mac telling me about iCal alerts. When I see these, my iPhone has already reminded me, because the iPhone is always with me.
I still want reminders to sync, so I can look at my list and add things while at my Mac. Fortunately, you can turn off alerts from iCal’s advanced preferences.