Wouldn't it be nice, if the birthday maintained in the personal address book would appear in the Notes Calendar?
Moreover, creating a birthday (anniversary) has always a strange touch, when I need to decide "how long this person may live". Other Calendar programs do create birthday "forever".
When adding a birthday/anniversay to a contact, there should be a button to add it to calendar as a recurring (75 years) reminder.
Although, now that I look, these fields are only initially available in the popup... OK AND the birthday and anniversary fields should NOT be hidden by default....