Codename D was revealed for Kinect during Tokyo Game Show, but nobody is sure what it is actually about - we don't know much except that it's at development at Grasshopper, supports Microsoft's motion sensitive camera and that it might have something to do with baseball. And fire and explosions.
"Codename D" was always a working title though, and now Siliconera has spotted that Grasshopper has filed a trademark for the title "Diabolical Pitch". We don't know that the two are related, but it seems pretty natural that they would be.