[quote name='donssword']Someone from Gamestop can chime in and correct me on this if I am wrong, but I believe the items for sale come from a new or recent wholesale buy, not from their existing stock or warehouses. [/quote]
Yes, I believe this is the case, as well. This means you'll also see lots of games from certain companies, as well. For example, I remember SEGA had a bunch of stuff last year, such as Sonic Rush, House of the Dead, Superstar Tennis, and Mario & Sonic Olympics. This probably means that first-party games won't be on sale, so not much chance on Halo 3 or Mario Galaxy on sale.
[quote name='donssword']This is why sometimes you will find the same game outside the sale bin on the shelves but not marked down, because the sale stock is a diff SKU. [/quote]
Yes and no. The games are usually outside the sale bins because they were already on the shelves when the new Gameday shipments came in stock. However, they will still ring up as the Gameday sale price, even if it's not from the bin. I'm almost positive the SKUs are still the same.
Also, this means that many of the games may still be available with shrink wrap (I.E. not gutted) when the sale first starts, but employees will sell those to customers first, so if you want a fresh copy, don't wait for the prices to go down a second time.
Most likely, GameStop corporate will instruct stores to gut the games so that they can be displayed at the front in the bins (where things are easily stolen). Additionally, they will get a bunch of special price stickers (that are more sticky than they should be) that need to go on the gutted cases. Everyone I know who works at GameStop hates these stickers with every gaming fiber in them, but there's really nothing we can do about it.