I think its important for parents to tell their kids that yes they're special, but no one is perfect. My parents told me that I was special and smart and all of those things, but I am very well grounded in the fact that you get out of life what you put in to it. I accept my grades as what I've earned without question (unless there really is a mistake, and even then I try to approach it in a very respectful way).
I agree that some kids are raised to believe that they're the greatest thing to grace the earth. Life is going to be very hard for them once they enter the real world.