The 1Q 2008 Long Island/Queens Market Overview [pdf]  that I author for Prudential Douglas Elliman [PDE]  is available for download. We took over the preparation of this market area study for them in 2Q 06.
You can see the methodology that went into the report.
..Price indicators for the quarter will mixed as compared to the same period a year ago. The average sales price was $514,135, up 3.6% while the median sales price of $435,000 was down 0.6%. The number of sales were down 14.1% to 6,015 units while inventory levels were up 10.2% to 35,209 units. A weaker economy and difficulties with access to credit have tempered the demand for housing compared to the past several years. The expansion of the days on market indicator and rising inventory levels are the result of reduced demand, yet the pace of inventory growth is easing. The next quarter tends to be the most active quarter of the year as characterized by elevated sales activity and price growth…
Download report: 1Q 2008 Long Island/Queens Market Overview [pdf]