Trying to understand Fannie and Freddie?

An interesting interview, that could make you very angry, is linked here. A quote for the flavour: Nearly all real estate experts are in agreement that for the next year or two, many of today’s homeowners will find themselves locked into where they are now living. Their situation is much like medieval serfs were tied to their land. They can’t sell, because the market price won’t cover the mortgage they owe, and they don’t have the savings to pay the difference.