You know this movie sounds an awful lot like Goldberg's "Santa's Slay" in plot. In that movie Santa is a demon who lost a bet to an angel and was forced to spent centuries doing good deeds, with the movie picking up when the time limit for the deal has expired.
Oh and while less thematically similar:
http://www.youtube.com/watch?v=9yx0wIS1iOg
A timeless Christmas Classic for you all to enjoy (Thanks Wierd Al!).
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While far more obscure I also remember reading a short story about how Santa was actually the Devil (literally) and he did pretty much all the things in the stories, but the toys and such were manufactured by the souls of the damned as their torment. Can't remember the name of the book it was in though, whole series of short story collections that was published by White Wolf if I remember (not WoD related though).
Update: Ooops, well someone beat me to the "Santa's Slay" bit.