I have the same issue. With the new versions of operating systems for iphones, airbooks, and itunes, it seems they've changed how calendars sync, and they don't give you any way to adjust the setting. This is a PC kind of move. I've noticed that apple is beginning to make PC type mistakes a lot. I hope this is not a trend, now that I've just converted.
I could use help. Calendar is the most important feature for me, and I converted to Apple because I was told that their devices all worked together seamlessly. Clearly not.