Yep, it's just business. They want to slow oil production in the U.S. and Canada by selling it cheaper than we can produce it. It'll also likely stop the keystone pipeline if the price remains around $70, at that price the Alberta oil is too expensive to extract so there'll be no need for the pipeline.
It also has the effect of royally putting the screws to Iran and Russia, which is another big win for the Saudis. To tell the truth, I'm not sure what's really their target, the domestic U.S. oil industry or Iran. Maybe it's both.
