I preordered the new Harry Potter book months ago. I was surprised to get this email from Amazon today:
Good news! We've just lowered the price of "Harry Potter and the Half-Blood Prince" from $17.99 to $16.99. You don't need to do anything to get the lower price--we are automatically issuing you a $1.00 refund.A retroactive discount? That's a clever way to build business. A quick search reveals Amazon is now undercutting the other major stores on price.
In related news, you can steal the new book electronically if you like reading OCRed pages. A torrent of an audiobook version (lovingly read by a robot, one presumes) has 2000+ downloaders.