Below is a chart showing the distribution of ARM (Adjustable Rate Morgtages) based on the type of buyer rating. It is a powerful graphic to help you understand who was getting what kind of loan. If you take time you get to see what kinds of borrowers got 'teaser introductory rates' that reset within a matter of months, and who were getting the 5 year ARM loans ideal for refinancing a home you intend to sell before the rates reset.
ARM loans are great tools for shorter term situations and there is little else I can add to the swirling conversation going on right now. However any futures systems thinker could have looked at this graphic with a quality legend and told you that this is bad news. A futurist could have looked at the indicators and drawn up only a select few scenarios in which this lending profile was sustainable. Hopefully organizations and institutions will implement a bit more foresight particularly when a potential end scenario is mass repossession and eviction of homeowner.