They also were done using an X3100 that could share up to 256MB of memory. Apple restricts memory sharing on the MacBook to 144MB...this would produce lower performance, obviously.
The sharing issue is easily the biggest problem - VRAM is much much faster than shared system RAM. If Intel were to release a version of the X3100 with dedicated VRAM we would see a pretty big leap in performance.
25 fps is acceptable to me as a single player game. So I hope in June we will finally get a Macbook revision that allows decent 3d games to play good enough.