Coming from a Rolling Stone interview...
"With Pikmin 3, you'll have the ability to have three different captains or leaders of Pikmin groups and you can switch between them. So it sort of allows you to approach the game from a much more strategic position. The volume of work that you can get done within the timeframe has increased dramatically. And so that in and of itself really enhances the depth of strategy that's available to you in that game." - Shigeru Miyamoto
Oh man, that makes me a bit nervous! I have trouble enough making sure Olimar gets the job done with his Pikmin. Now I have three captains to worry about?!