It was news to me that retirement accounts are protected against judgment. Looks like it's not a complete shelter, but good enough for purposes of current foreclosure [1].
Of course, living in a non-recourse state is probably the best move, as you can't be held liable (your real estate secures your mortgage).
Something to note: Retirement accounts are not shielded from taxing bodies (i.e. the IRS).
Somewhat offtopic: This is why I always recommend people use a Roth IRA as a savings vehicle vs a savings account. Not only can you withdraw the contributions at any time, but its shielded from creditors. Your ability to use a Roth IRA is, of course, subject to income limitations.
Of course, living in a non-recourse state is probably the best move, as you can't be held liable (your real estate secures your mortgage).
[1] http://finance.zacks.com/retirement-account-judgment-proof-5...