i would walk away from the mortgage payment completely

1. you house is underwater with 0 down, you have no equity. if you walk away, you would have nothing to lose except your credit.

2. you can't refinance into a tradition loan

3. it will take on average 1 year to foreclose, you can technically still live there 1 year rent free and save around 30K cash.

4. if you live in a non-resource loan state, bank can do nothing to you.

i would just walk away, no reason to throw good money after bad. you can either rent or buy a new one with money you saved.