I do believe the last day is Sept 22nd, meaning you had to check in by that date. The free dining would run the length of your trip. BUT you had to book the promo by June 24th.
I just re-read your post, LOL, you are going 2008. I booked in Jan 2007 for Mid Sept in the hopes the free dining would be offered again. You can hope it will be offered Sept 2008. Just make sure you switch your package to include it if it comes out. Thats what I did when the offer came out.