Well, neither Xith3D, Java3D nor jME are "game engines", they are more or less graphic libs, adding some sound and math and behavior functionalities.
Well, if SQUEAK is a game engine as per their definition you gave, then jME would also be a game engine as it provides all of those features as well.....
My question I think is still valid....nothing I have seen mentioned in that CVS description gives me any idea what it will provide that isn't already contained in a pre-existing game engine.
-Matt Hicks