"We got it to work, but it was too late in the development cycle," Cook said, presumably talking about the cycle of the DS game. If only they'd thought of it sooner, he laughed. "It's one of those things where you just kick yourself."
Basically, Rare was able to get the DS and 360 to talk to each other with the 2 new Viva Pinata games, but it was too late in development to get it fully in.
I doubt it would've ever made it beyond the testing room. I just can't see Nintendo and Microsoft doing a collaboration game like that. At least not now.