I went for a look around today, I had no trouble find any 3 of the 360 skus. I even spoke with a few workers which told me they never run out of 360 stock.
End of 2009 Predictions (Set, January 1st 2009)
Wii- 72 million 3rd Year Peak, better slate of releases
360- 37 million Should trend down slightly after 3rd year peak
PS3- 29 million Sales should pick up next year, 3rd year peak and price cut