Why does it matter, what advantage is there for chess to be 64bit?
Chess is 64-bit (it is in Lion, too), but Grapher is still 32-bit.
Chess actually has fullscreen support this time around (it was one of the advertised features for Lion, but never actually happened)!
Those were actually two questions. The first one about 64bit support in Grapher and the second one about anything new in Chess. Sorry for the confusion.