Hmm... I think it all depends on how you were raised. I wasn't raised in the U.S. and my parents neither told me about the existence or inexistence of Santa Claus or of any of the fairytale characters for that matter. However, they did give me a lot of books, all of them were of different views, beliefs, themes, goals, etc... in other words, the books I read did not have the same types of characters and stories.
All my parents told me when they gave me those books were that 1) Books and stories people write are very powerful, they can make you believe and/or destroy your beliefs, so it's my choice to decide, 2) I should pay "very close" attention to each book/story I read because even though the stories might be completely different, all have a similar message, and 3) Imagine, don't just picture.
But I think rather than telling them that Santa is real or not real when asked, one may want to try and ask the child what s/he believes. If the kid cannot decide for him/herself, might as well tell him/her the truth. It's always a better policy than to lie.
Lastly, one suggestion I'd like to give you is, when you believe in something, or someone, ask yourself "why" first, and how "important" that particular belief is.