How do you get the Disney castle pin on club penguin?

You have to unlock it. Basically, you have to buy a certain toy or item (most Club Penguin items can be bought in the Disney store, Game, Sainsburys, WH Smith etc.) Using the code that comes with the item, you can get the pin. Very few penguins own this pin, and I'm not sure if it is still available in 2011, although it may be.