The announcement, as translated by IGN, goes on to cryptically state that "even if you don't play it [as in control the game], the world and the LocoRoco will play [as in both playing amongst themselves and as in playing back like a video] on their own." So is it a game? A glorified screen saver? A virtual LocoRoco ant farm? Who can say?
Whatever form it takes, the "game" will use Sixaxis motion controls and should be available as a PlayStation Network download soon.