Well it is a discount, but not the special pin code you were probably hoping for. That is for the 4/3 deal they have been advertising since last year, and it is available to the general public. It appears they are now emailing it out (desperation?). All the general public discounts are 3 letters. You can check out Disneyworld.com for these codes at any time.
The discount pins that are specific to you are more than 3 letters - they are a series of numbers, and are approximately 15 characters long. These are usually the big money savers, and are more difficult to come by (and are seemingly random). The current booking system is capable of recognizing the phone number of the phone you are calling from and determining if there is a matching pin code right off the bat. If you have a pin attached to your name specifically (or more accurately, a pin attached to that phone number) it will ask you to dial it in at the tone.
Good luck in the pin hunt! I myself am hoping for
free dining, but am fortunate enough to have a 40% off pin for the time being. Make sure to get yourself on as many email lists with Disney as possible.
Booking and canceling soon after doesn't hurt either! Although I've never done this for this explicit purpose, both times I have had to cancel I have received pin codes via email (and those are the only times I got them).