Go straight to the source, don't get the run around and mis-interpretations from other places.
Sprint Newsroom | News Releases
As I understand it, those are locations that will have extra launch festivities. Some stores in those markets will be opening early at 8am and will have things going on throughout the morning and early afternoon related to the launch and sale of the Evo 4G LTE. The rest of the country will be opening at normal Sprint hours and will operate as usual, selling the Evo 4G LTE as well.
I don't find it a coincidence that many of these 8am stores are located in or near markets that are scheduled to get the LTE rollout first.
Don't quote me on any of this, but it wouldn't surprise me if there is an LTE preview in these stores. Possibly swag and giveaways? Demonstrations and feature guides? It would also be extremely awesome if they had a location or two set up to test and demo HD Voice like they did at the reveal party in New York.[/speculation]