Here's a very interesting article about that might affect anybody considering walking away from their home:
http://money.cnn.com/2010/02/03/real_estate/foreclosure_deficiency_judgement/California is a non recourse state, but if you refinance, or the bank can prove that you've rented your home, you might loose your non recourse status. Even a loan modification could put you into a "recourse" status.
Beware of banks bearing gifts. If the bank offers anything short of full payment of a loan, it's because it's in their interest. You need to protect yourself to make sure you know what they know.