Additionally, I've gotten refunds on pre-orders which have dropped in price the day after they've shipped. So yeah, you get the lowest price during the time you've been on the pre-order, and a short time after.
An update on exactly how this works. The "short time" is for pre-orders which ship before their release date. Many movies and games when ordered with two-day shipping will ship on Monday in order for them to arrive on Tuesday. If the price does down between shipping (when you actually get billed) and release, you'll get a refund for the difference.
