Here is the latest numbers on housingtraker actually, the inventory has been going down since July, the numbers now closer to 19k. Maybe folks pulled their homes(off the market), waiting for spring '07?

 http://www.housingtracker.net/askingprices/California/SanDiego-Carlsbad-SanMarcos/

Trend 11/06/2006 1 month 2 month 3 month 6 month –

Median Price $525,000 0.9% -1.9% -2.3% -2.6%

Inventory 19,934 -5.8% -9.5% -8.9% +7.6%