We have a big problem with greedy lenders, greedy CEOs at major banking organizations, and people who didn't take responsibility for checking out their own finances before buying a house that was way out of their reach given their income and available resources. Lenders gave people who really shouldn't have had loans those home loans, and people took them. When housing prices started to fall, it meant those loans were now for over-valued products, and people couldn't sell their homes without taking a huge loss, so they were stuck with huge loan payments and no way to get out without defaulting or bankruptcy.
This isn't an Obama-McCain issue. It's a massive problem starting with:
de-regulation in the '90's
inadequate or complete lack of appropriate oversight for Fannie Mae and Freddie Mac by the gov't when it privatized these agencies
fraudulent or inappropriate lending (who in their right mind thinks it's good business practice to give someone with no job, no income, and no assets a home loan????)
fraudulent mis-statement of earnings by CEOs in some major investment firms, incompetent management of some other major investment firms
fraudulent lenders in some cases
some buyers taking out loans for more than what they could afford and abdicating their personal responsibility to do their homework on what they could truly afford
an oil crisis these last 2 years driving up prices on everything and causing an economic problem that affected people's ability to repay their loans, particularly those who were in a fragile financial situation to begin with
Congressional leaders on both sides of the aisle sticking their heads in the sand when it was clear a couple years ago that action was needed to forestall this crisis
probably there's even more I'm missing than what I've listed, but it's definitely much more than either Obama or McCain, and the solution is going to be much more than either of these men will be able to effect as President, too.