TBP: How Lending Standard Changes Led to the Housing Boom/Bust

"The perfect storm of ultra-low rates, securitization, lax lending standards and triple AAA ratings -- these are the key to how we ended up with the previous boom, followed by a bust, and ultimately, the credit freeze."

Barry Ritholtz at The Big Picture provides the most non-political, straightforward and easy-to-parse explanation of the real estate mortgage bubble and subsequent credit crisis I've seen to date.