We still have a number of stories in the collection that are under 1000 words, sometimes only by ten or so words. We do determine length based on the AO3's measure, so even if your word processor says you had 1000 words, if the AO3 reads it as fewer, then it may need to be a little longer! A story under 1000 words should go into Yuletide Madness 2010 (when it's open) even if it's a second story for your assigned recipient.
Some of you may have received early notifications, if you were part of the Dark Agenda challenge-within-Yuletide challenge.
There's more about that over here. It wouldn't be Yuletide without a few hiccups, would it?