[quote name='thesuzukimethod']also, can we
please stop with the "why is amazon screwing over pre-orderers?" line of thinking. it's a
known fact that amazon uses algorithms to determine pricing...
and this LA noire pre-order/order bonus is probably no different. Probably a set of pre-sales thresholds that triggered the credit increases, and one trigger just happened to be met the day after launch
I am sure they would have preferred this not happen this way, given the possible backlash. and as the link mentions above, their robo-pricing is not without flaws.

[/QUOTE]
You are completely wrong.
1) Amazon offers that automated pricing system to 3rd party sellers, not on merch they are selling themselves.
2) The price hasn't changed at all, only the value of the promotional credit has.
3) This is entirely the result of other retailers offering increasingly better higher promotional credits and then amazon matching them....first Best Buy a $15 GC for online orders last week, and then walmart offering $20 GC for online orders I believe yesterday.
4) Your logic is completely off. If they sold a ton of pre orders, why would they up the promo credit after the fact? They were presold, so it is not like they have warehouses of full of them and now they need to some how throw on extra promos to move them.