N.VA low end houses going up, but high end houses

are still lingerring. I've followed the houses priced at $200K-$280K very closed since Oct. 2009 for interest in buy, it happened that house inventory at this price is Extremely low now compared to 6 months ago. However, the high end houses (1 million or so) are still slow in sale and high in inventory. I heard that mid to high end house owners might walk away from mortage, which can produce more short sales. Would it push down the price and affect the low end houses? Or they can go each way separately? Appreciate your thoughts.