That really stinks. But you should try different dealers. My experience:
In September I went to 2 of my local Ford dealers. One of them had an '05 on order since February, including a deposit on it. They had no idea when it would arrive, only knew that the order had recently been changed on Ford's end to be an '06 model. They told me that I could order one, but it could be forever before it arrived. The 2nd dealer had 3 GT's but all 3 were pre-sales (sold). They too stated they could order, but it would be a minimum of 2 months and likely 6 months they said. I passed on that deal too......
I ended up going to ford.com and doing searches by zipcodes that I knew for being within a 200 mile radius; I found multiple dealers that had several GTs to choose from; I ended up buying my '06 around Labor Day.
If you're outta luck with any dealer within driving distance and are really considering buying something besides a Mustang and you want a 'vert, the Nissan is a nice car. Unfortunately there isn't many performance oriented 'verts available. However, if you can find a GT vert at a different dealer, do it; you won't regret it.