Nintendo World Report notes that the game will have a two player download play feature, but whether this is for the full asynchronous coop mode or for the Mario Bros. "versus" game is yet to be seen.
Unfortunately, it looks like it's not the GBA version of the game, which means it's the same version you've played a million times before. Even so, my wife and I have beaten it annually for many years, so having this classic on the go isn't a bad thing. That is, if a western release is in the cards.
Super Mario Bros. 3 [Nintendo World Report]