If I ever have children, I don't think that I'll let them believe in Santa Claus. I mean, let's recognize the tradition for what it really is_
In order to encourage behavior modification, parents tell their children the following story_ A omniscient being will keep track of their every action, and judge it against an arbitrary set of standards to determine whether each child has been "good" or "bad". Then, this fictional fatherly figure will either reward them with fabulous gifts, or punish them by witholding everything good.
(Wait a minute, was I talking about Christmas or religion here...)
Seriously, though - Is this Santa myth more than just a way for parents to keep their kids under control and avoid being the bad guy? ("Well, I'm not going to punish you - but Santa will!") Wouldn't it be much better to explain the holiday as a time when people gather to enjoy each other's company and to exchange small tokens of their love and respect? Why isn't that enough?