Nintendo's E3 website reveals a few things and clears up a couple of mysteries regarding the sequel to Pikmin.
Nintendo of America's new website for E3 2003 contains a Pikmin 2 feature, in which a few bits of are dropped.
The story has Captain Olimar returning to the Pikmin's world, this time voluntarily. His business is going under, and he needs to dig up treasures to pull out of his debt. Olimar has brought along an assistant, already seen in screenshots, to help save the company. This assistant is still not being called by name at NOA.
The feature goes on to clarify some gameplay details too. As we expected from the first batch of screenshots, there is a two-player cooperative mode in which each player controls one of the spacemen. In the single-player mode, you'll switch between them, possibly for Lost Vikings-style shenanigans. Another huge departure from the original is that there is no time limit in Pikmin 2. Presumably, there will still be a day-night cycle, but players will no longer be restricted to thirty days in which to beat the game. It's currently unclear how the game will balance out this change, whether it be more complex tasks, harder enemies, more levels, etc.
Of course, you couldn't expect a Pikmin sequel to leave out new colors of Pikmin, new enemies, and new types of environments. All are present, as you'll see in the new screenshots.