Children are always so intrigued and I believe that it is important most of all to stimulate their mind into scientific enquiry.
My father often used to show me the magic tricks that are performed on the television sometimes in late night shows. He always encouraged me to wonder how the illusion was being acheived; and discouraged me from believing that there was any non-physical explaination. But he never himself told me what the trick was until I had already tried to figure it out.
There is some room for such in stimulating childrens scientific enquiry then, but of course this is being done more by parents than by that so called magician.