So, after reading through this, it looks like MS wasn't planning on selling out of the ~2 million EA Sports bundles before Christmas like the past two years and is now getting burned. I think they planned on only selling ~600k last month leaving plenty for Dec. When the Nov. numbers started coming in, it looks like they were able to start getting the vanilla system back in the channels barely in time. It's been hovering in the top 5 at Amazon the last few days and wasn't inflated up to near $300 like the EA sports bundle until now. Ordering for one after the 25th will still be a problem, but not nearly as bad as it was.
Anyway, MS missed out on a chance to pick up some extra marketshare this holiday while only pushing Halo 2 (that's the only Xbox ad I've seen for a while), where PS2 has has the benefit of a lot more MGS3, GTA: SA, and Killzone commercials the last few weeks. I'm not sure how bad the damage is, but if MS doesn't do at least 1.24 mil for Dec., then they really messed up the execution for this holiday in terms of getting more marketshare.