I just called my local Walmart and 3 people have no idea what time the iPad will be released. So my guess is that it'll be released similar to Black Friday DVD's where the warehouse wheels the pallet down the hall and the customers start a WWE match.
I called 4 local Walmart stores and they all said they won't know until Thursday night if they're even getting them. I have a friend who works there, so I'm gonna try to see if she can find out anything.