Just thought I'd give everyone a heads up about this. The Xbox is the next system GameStop is phasing out. Some smaller locations have already eliminated their Xbox sections, shipping the games to other stores. It's not too surprising considering that most of the Xbox games you'll see at GS are dirt cheap (and now that they're being phased out, they're going to get cheaper - see, there's always an upside), and the 360's lack of full backwards compatibility doesn't help.
So if you see anything that has a good chance of being gone before the discounts take effect, get it asap.
And in case you're wondering, I wouldn't expect Gamecube and GBA stuff to be phased out anytime soon due to full backwards compatibility on the Wii and DS, and we all know that the PS2 is still doing pretty well.