@JWL3. I've preordered DOZENS of games. The preorder charge is deducted at time of purchase from the CURRENT price at that time, not from the full MSRP. If the game shop or retailer chooses to discount the price on the first week (extremely rare for popular games), then you in the end pay the exact same price as everyone else, get some bonus things, and are guaranteed a copy (in rare cases, preorders are so high they're doled out over a few weeks).
You also have full rights to get a full refund of your preorder "deposit" should you choose not to take the game afterall. It must be refunded. they can;t keep it. So, if they refuse to price match a current sale from another retailer, you buy the game at their competitor and get you money back. This may mean you have to wait until games are in stock, but almost every reputable retailer has a prioce match guarantee and is bound by advertising laws to give you the game at the lowest advertised price minus your already paid deposit.
@hellwig: I agree nearly completely. Bonus items that give early adopter in-game advantages in multiplayer should be banned, ESPECIALLY in cases where monthly fees to play are involved. I don;t mind unlicking bonus levels, mini-games, single-player mode special weapons, badges of honor, and more, but giving players advantages in multiplayer should be completely banned, voluntarily by the gaming industry.
The real purpose of preorder promotions by the way is to guage retail demand so they can produce an appropriate amount of games to handle initial demand surges. It's completly to the distributors benefit to have you preorder. SOME incentive needs to be used to get you to preorder, and lets face it, cheezy posters don't really cut it for most people in today's world. Still, some incentive is necessary.