Keep in mind that wal-mart only has a limited amount of shelf space in the area where they sell movies, so they aren't going to stock their shelves with products that most people aren't going to buy. Until there is a clear winner in the format war, I don't forsee Walmart stocking too many BD or HD-DVD discs in their stores. But it IS good that they are offering a quality name brand player for such a competetive price, wether you like walmart or not, it's good for competition, and could further drive down the prices of other players, both BD and HD-DVD.
And since those players will also upconvert standard dvd's it would make sense to buy a player like that instead of say a $200 oppo upconverting player. That way you have a nice upconverting player, and the ability to play HD-DVD.