I don't think we're at a tipping point yet. Amazon sold Kindles to its most regular book customers. We'll reach a tipping point when the general public begins t

I don't think we're at a tipping point yet. Amazon sold Kindles to its most regular book customers. We'll reach a tipping point when the general public begins to purchase ebooks, but I don't think we're there yet. We don't know how many of these purchases are to Amazon's best customers. I would be very curious to see the purchases broken down by the number of customers purchasing ebooks vs those purchasing paper books. And by quantity, how many ebooks are purchased vs paper books per customer. Is this simply a fact of frequent customers now buying ebooks, or many more customers now buying ebooks.