Take a look at this report from Fitch, the ratings agency....
Fitch, in a downgrade of yet another 543 mortgage-backed securities of 2005-07 vintage, gives us the following side notes: "The home price declines to date have resulted in negative equity for approximately 50% of the remaining performing borrowers in the 2005-2007 vintages. In addition to continued home price deterioration, unemployment has risen significantly since the third quarter of last year, particularly in California where the unemployment rate has jumped from 7.8% to 11%... The projected losses also reflect an assumption that from the first quarter of 2009, home prices will fall an additional 12.5% nationally and 36% in California, with home prices not exhibiting stability until the second half of 2010. To date, national home prices have declined by 27%. Fitch Rating's revised peak-to-trough expectation is for prices to decline by 36% from the peak price achieved in mid-2006. The additional 9% decline represents a 12.5% decline from today's levels."