The big lie regarding this matter is that it was all the fault of the free market. The talking point, coming from both McCain and Obama, is that the greedy bastards at Wall Street did it. It's easy and politically convenient to blame "Wall Street" whenever something goes wrong, and certainly they share part of the blame, but this misses the root of the problem. The problem was never the free market.
You may ask yourself why were so many of these big, elite banks willing to give out these highly risky, ill-advised loans to a subprime community that had no business owning homes? Answer: because they could simply sell these mortgage loans to Fannie & Freddie the next day in the form of MBS (Mortgage-Backed Securities).
You may then ask, why were these elite corporate moguls at Fannie & Freddie willing to buy such crappy packages? Answer: because they have always been government-supported (they had "implicit" government backing, which is quite an understatement) and knew that if everything went south, the government would bail them out with taxpayers' money.
What we have above isn't the "free market" at work. Rather, it is a gross socialistic distortion of the free market via aggressive government intervention, both in terms of financial backing and policymaking.
After all, it was the government that interjected itself into the market and pressured the financial companies to give out risky loans to subprime borrowers, under the ideological feel-good mantra that even the poorest people and those with virtually nonexistent credit ratings deserved to own homes. The Clinton administration supported it via the Community Redevelopment Act, and the Bush administration perpetuated it. This governmental policy pressured the financial companies to handing out foolish, high-risk loans at lower interest rates, and it certainly didn't help that companies like Freddie & Fannie were essentially playing with taxpayers' money, counting on a bailout.
This isn't a Republican or Democratic problem. This is a government problem. Both parties supported and tried to take credit for these governmental interventionist policies when things appeared to be working well. Now that things are looking less rosy, the government tries to divert the blame for their own foolish policies and attempts to use the situation to justify even more governmental involvement.
I am in no way absolving the financial institutions of their share of the blame, nor am I absolving the irresponsible subprime borrowers for pouncing on an opportunity to buy a home they should've known they couldn't afford, but the government - along with both the Democrats and the Republicans - was the catalyst behind the entire problem, by distorting the free market and propagating an unsustainable policy of foolish lending, artificially low interest rates, and the implicit promise of a bailout.