The first part of the video shows off the Wii version and gives us some of the basic plot line. You play as one of the Edible Mushrooms during a civil war taking place between the Edible Mushrooms and Poisonous Mushroom. The most interesting part of the trailer shows off how players will be able to take items the Mushrooms have found from the human world and create different type of weapons out of everything.

Whereas the Wii version will be a giant fully explorable world, the DS version is going to be a side-scroller set in a 3D world. The DS version will be a prequel to the Wii version and looks to maintain the same weapon customization. 

So far, so good. A lot of buzz has been going around this game so it'll be really interesting to see the final product next fall.  

[Thanks, TheGoldenDonut!]