I think what you mean is that future games will take advantage of the SD Card. Nintendo already announced Animal Crossing e+ where you can download/upload items from other people, clothing you made, etc.... And if SD prices get cheaper, you can go on the net and download another level to a game like say Metroid. Lets say Nintendo or Retro want you to be able to play a level that they didn't get the chance to put into the full game. They could have you download it and then you can play it. Basically the setup would be similar to the XBox and how you can save updates to the HD. Except with the 'Cube, its more "functional". Now all I have to do is restart my PSO character and use the SD card, if Nintendo ever releases it here.
