Rare has updated their official website with some details on the new Viva Pinata DS, including this first screenshot:
Other details revealed in the update are that the game will feature the complete range of pinatas found in the 360 title and more – and that in addition to the sandbox-style gameplay found on the 360 there will be an "Episodes" mode that follows along with the Viva Pinata cartoon series.
And yes, I know that this news isn't strictly Xbox-related. Just keep this in mind: if the Viva Pinata franchise is successful on the DS it will be back on the 360 in no time.