as far as I can see, the top end of the market is experiencing the most price drops at least here in South Orange County. I have seen $1.2 million houses purchased in 2005 listed now for a loss at $900k. A lot of speculators in that market as well. The top end is getting hammered just like the lower tiers.
As for the statistic about so many buyers for top end homes, using that view is erroneous. I would bet that MOST people with $1 mil. liquid net worth are already homeowners and not creating any significant new demand.