Just three years ago, Marin county residents were busy raising money for a legal fight to stop Habitat for Humanity from building four homes affordable to families making under $56,000/year, saying it would “blight” their exclusive neighborhood of million dollar plus houses. (The project is still being debated.)

But now they are being welcomed with open arms in another part of the county as they renovate one of the foreclosed homes that even Marin has acquired a passel of. Habitat bought the house, which needs extensive rehab, for $215,00. It doesn’t sound affordable exactly to those of us in more affordable parts of the country, but in a county where the median home price is $800,000, I guess it qualifies.

Nothing like a wave of foreclosures to change those “Not In My Backyard” attitudes. This, by the way, is what affordable housing looks like in Marin.

As the Marin case shows, high-priced homes are increasingly going into foreclosure. Don’t be surprised to see Habitat next in a place like Palm Beach, Fla. Or maybe the group will take on even more foreclosures in Marin. The one constant about this crisis is that no region escapes its reach, even neighborhoods that once thought they were safe. For some once-exclusive cul-de-sac communities, it may be time to drop the NIMBY attitude,  roll up your sleeves,  and help out with the Habitat renovation.

Just to show you how bad the crisis in vacant and foreclosed has become, Habitat for Humanity is still around, and still helping out — only now the group is concentrating, in some places, on tearing houses down, The New York Times reports. The organization is already hard at work at this effort in Saginaw, Mich., a city plagued by abandoned properties.

As part of an agreement with the city, and with at least $500,000 from the state and federal governments, the Habitat for Humanity volunteers and paid workers plan to demolish two vacant, dilapidated houses here a week, every week, over the next two years. As for creating homes, they will build or refurbish eight houses this year.

The shift in the organization’s focus is a sign of the times in Saginaw, a shrinking city northwest of Detroit where at least 800 houses sit empty and doomed, and offers a glimpse of what increasingly empty neighborhoods in many cities may soon face as foreclosures continue.

International leaders of Habitat for Humanity, an organization more than three decades old, say their focus is changing to meet the demands of a changing economy. In cities where so many homes sit empty, the group is leaning away from building new houses and instead fixing up old ones, said Ken Klein, the vice chairman of the group’s board.

At least Habitat is out there, doing something about this. There’s much more Congress and the Obama administration could do to help out as well. It’s not an impossible task. In April, New Jersey will begin, for the first time, requiring a bank or other entity that forecloses on a house to take responsibility for it both before and after it becomes a bank-owned property, or REO.

Lawmakers could easily require banks receiving bailout funds to take care of their neglected REOs, as a condition of getting the money. Public shame, which worked in convincing some AIG executives to give back some of those bonuses, might also work here. Pass around a few photographs of trashed houses owned by Citigroup, Wells Fargo, etc., and it could go a long way in prompting some action.

The government could also get behind cities that are trying to stop banks from dumping their dilapidated REOs on the real estate market at fire-sale prices, claiming the practice has become a public nuisance because it causes a death spiral of falling property values. Washington, in addition, could support the idea of a federal land bank, or  land banking efforts in general,  so communities could more easily acquire and reuse large inventories of vacant homes. Fannie Mae and Freddie Mac’s new policy of not automatically evicting renters from foreclosed homes was a huge step in the right direction – but there have been few other innovative rental ideas coming from the government.

The worrisome question is not so much what Washington eventually will do — it is when will it finally get around to doing it? How many cities will be left scarred by vacant and abandoned homes before someone acts?