Just what you have to purchase from AAA to get parking in the Diamond parking area depends on your local AAA. Some people have been able to get them by asking when they purchased tickets from AAA; some people have been told they have to purchase an entire vacation package. AAA had an insert in the Sunday Minneapolis paper that indicated "black-out dates apply" to the parking passes (but didn't indicate what the black out dates were).
At any rate, you still have to pay to get into the lot. The AAA parking just gets you better parking once you are in. (Parking is free though if you are staying on site or if you have an AP).
PS. AAA is still worth it for the peace of mind knowing that you can call and get help when you need it. They also have discounts at other places like for oil changes.