The Biggest Day in Book Publishing?

As I anticipated in a previous blog post, Dan Brown's "The Lost Symbol" was a huge seller on its release day Tuesday, with over 1 million copies snapped up by consumers who value plot twists over character development. Ka-ching! No surprise there. As Motoko Rich notes in her New York Times article, what is really interesting is that the Amazon Kindle edition actually outsold the hardback when excluding the pre-release orders, far surpassing expectations in the publishing world. Have we crossed the Rubicon in e-book popularity?  How likely are YOU to buy an e-book over a traditional print book?  Does it make a difference to you if it's a novel vs. a biography you'll keep for reference, or a school text book?  Or are you only interested in an e-book reader for news publications?