One of the best primer's I have heard to explain the "Commercial Paper Market" was on NPR's "This American Life". To really understand what is happening in the economy you have to understand how this money moves about. Then you get why it's such a big deal that it seized up.
Of course I can't share all my sources with you since my best source is my sister Jen. But listening to this show will explain a lot for people who a) don't work in this field or b) don't have access to Jen.
Listen to "Another Frightening Hour About The Economy"