Well, here's what I saw when I checked out the Wal-Mart in Honolulu on Keaaumoku Street today [Monday]:
When I went to the store at around 9:30 a.m. HST, the display was still wrapped in its cardboard. One of the employees came to take the cardboard off the display, which is when I snapped the picture on the right.
Most likely by the time this is published, the iPhone 3G should be out on display. But it was interesting to see that the kiosk had not yet been set up. So, that's what you're looking for when you go to Wal-Mart.