OK here's some info:
You are a gardner and you start out with basic tools and land. you can develop the land, build ponds, makeflowers, trees, grass, slopes, etc. and it will attracht 'pinata's'. There is 60 pinatas species all with their own prerequisites.
So you collect them, then you name them and customize them, but there is also bad pinatas. They will make trouble and you will have to fend them off, if you cant do this alone, you can get help from people in towns they also sell you goods, or you can go on xbox live and ask your friend to help you and you can landscape together or drive off the bad pinatas together.
Damn, is this CUTE or what? I love it.
EDIT: so the game is about collecting, interacting with the pinatas and harmony with the enviroments you create. it's a changing world.
Also the gardens are in a persistant world so you can leave your garden to roam someone elses, it seems.
Holiday 2006 worldwide launch.