I'll be getting a serious four-player romp around Thanksgiving.
There's good news for people who know things about modifying games, too. Due to the early Australian releases, there's been significant progress into learning how the game is programmed and designed, so preliminary modification tools are apparently available already.
My hope is that someone goes through and recreates several, if not all of the prior Mario Bros. games, with modifications so they can handle four players. I'd suppose the bosses couldn't quite be remade, but it would be interesting. Extra enemies would probably need to be added, too, but it would be pretty remarkable if all of those stages could be added into the game.
Truthfully, I think Nintendo might consider such a thing themselves. In all fairness, the game is less than half a gigabyte in space, so if Nintendo decides to revisit the New Super Mario Bros. franchise on the Wii, they could easily do a retro-remake compilation. I'd pay for it, at least.