The real-estate market is tied into employment. The Northern Virginia is in the high end for new expected jobs.
I read today that in February 2005, there were 7800 houses that changed hands in Northern Virginia. That figure was 7000 in February 2006. Prices aren't going down here, but it is taking longer to move the property....depending on the location.
But that you can sell your house at all and prices are noticeably higher than 5 years ago, you can give credit directly to Newt Gingrich for creating the capital gains tax exemption for homeowners. It freed up $1T in real estate and created the boom we saw this past decade.