And the pass will be turned over to look at the expiration date on the back. So you can't use old Annual Passes and just flash the front of the card. Since you aren't paying anything, you don't get a receipt so you have to show the pass at each parking entrance.
And remember that at any time, Disney World can ask you to show vaild photo ID along with your Annual Pass. I highly doubt they would for the parking but if it becomes a big problem with non Annual Passholders borrowing passes just for free parking, that very well could become a requirement. Please don't do that.