Many stores basically have to wait on allocation numbers, they don't want the same thing happening that happened to the 360. When sony gives them the allocation numbers (how many ps3's each store will get), which should be mid september according to reports, then they will start pre-orders. Right now, they just have a big black book (atleast in my local EB's) where they will take your number down and call you when it's time. Each store will get a certain amount of ps3's depending on the previous sales of their sony products like the psp or ps2. (basically, so they can find out which stores will need more)
I've heard, the more you put down (when the time comes), the higher you will be on the list. But that's just a rumor.
Another rumor is that the official sony store in CA isnt even taking pre-orders at all, some think its because free press for Sony when news channels catch hundreds of people waiting in line for hours at the biggest sony store around. Some speculate some kind of launch party happening the night before.
But yeah, around sometime in september (my guess around TGS time) you, me, and every one else will be able to pre-order in NA (EU is already allowing pre-orders, and some spots in canada). You may be able to find a Mom and Pop video game store who don't care about pre-orders to put your name on a list.
