I think the chance of iPhone 5 on VZW and AT&T at same time is really good
Seeing as Apple just unveiled the iPad 2 to be released on both VZW and AT&T at the same time, I think the chances of the iPhone 5 to be released on both carriers at the same time is really good.
Look at the situation. AT&T carried the iPad first followed by VZW a good while after. VZW hasn't even had the iPad on sale for that long and it will already be replaced by the iPad 2. I really don't see why Apple wouldn't have the iPhone 5 released on both carriers at the same time come this summer even though the iPhone 4 will only be a few months old on VZW. AT&T isn't getting a head start on VZW with the iPad 2, I don't see why it wouldn't be the same case for the iPhone 5.