Several local Gamestops (not just the one near me, but local to various people across IRC) are now telling customers that they'll be SELLING Doom 3 on August 1st. It's doubtful, but they seem adamant about it.
Most Gamestops I have called/visited have no clue about the impact that Doom3 will have. They mostly seem to think it's just another pc game. As with all of these kind of enterprises it's the teen that is being marketed, and most of them just have console systems.
But, it looks to me like you have a GameStop near you that actually knows what is going to happen. The three retailers: GameStop, EBgames, and BestBuy will all be getting priority shipments based on their pre-purchase sales a day or two before Aug 3rd (like on the 1st), so they can open up on the 3rd and hand them out. However, keep in mind that any GameStop allowing any copies out the door before the 3rd is violating their contract and may face disciplinary measures from Activision and/or idsoftware. If I go to my GameStop on the 3rd and ask for my copy of Doom3, that I've already paid for, and the yutz behind the counter says they are sold out I'm gonna be fragging mad!
I went to my GameStop just yesterday for a Doom3 rehearsal (the guy was not enthused) and he verified my pre-purchase and looked up the release date on his computer and it indeed said Aug 3rd.
Bottom Line: You've waited several years, so you can wait a couple more days.
Let's Rock!