From an interesting piece (found via Ed's blog) reacting to the Republican reaction to the Financial Crisis Commission's findings:

After 20 years of free-market fervor, the world of the mid-’00s had become one of overleveraged banks too big to regulate and trillions of dollars worth of derivatives bets that no one had track of — which in turn were helping to accelerate huge flows of capital coming in from abroad — and a Fed and government regulators who weren’t aware or weren’t watching.

And that was the real cause of the crisis, whose aftereffects continue to drag on the economy today. Fannie and Freddie were, like almost every other big player, both culprits and victims, but just two of many.