After reading many posts from this forum, I was able to try tonight for the first time and was able to secure a white ATT 16gb in Chicago.
Here are some tips:
1) The stock list gets updated 1-3 minutes before 10pm ( at least it did for tonight)
2) Add all the iphone of your choice into your cart ahead of time. I added 3 different sizes/colors on my cart.
3)A few minutes before 10PM (central) I started refreshing my cart, then I noticed my first store of choice had what I wanted.
4) I had my credit card store and sped thru the check out.
5) Victory!!!
in step 3) you can also click on the 'Change Store' link. This will show a pop up with the store listings based on the zip code. You also have a drop down where you can select another one of the phones that you had previously added to the cart.
Good luck all. Hope this helps someone.