That isn’t all that is still undefined, according to PopCap. The company says that it can’t yet confirm the launch platforms for the tower defense sequel but they do have it in development for multiple platforms; and while they did not say as such, we expect that it is likely in development for the same platforms that got the first Plants Vs. Zombies as well as some new platforms.
While the sequel will arrive in early 2013, this has nothing to do with the rumored Plants Vs. Zombies multiplayer console shooter that is said to be in development by EA’s Black Box studio. While we know that Black Box is working on it, we have no clue when this might be coming. It is apparently still in development and isn’t related to the Plants Vs. Zombies sequel.