I have been there for a few birthdays and the only thing I know of is the phone call from mickey (or maybe goofy) in your hotel room. And of course at guest relations in MK (and probably at all the other parks) you can also recieve and phone call from one of the characters as well as recieve a birthday button to wear for the day! This button sometimes inspires cast members to be extra nice and even sometimes move you to the front of the line! Thats not set in stone it just has happened to us before. We were also able to buy a birthday cake at our resort. Otherwise it seems you may still have time to book a special dinner. Next week we are going and it happens to be my daughters 13th birthday so we booked the luau to celebrate her Bday, thats just something we have never done before. Good luck and definitely ask the front desk about birthday ideas, they are always dreaming up new ways to spead magic.
renee