Nintendo DS, Map utility?

Apparently there is non-official software currently in Japan for the DS that shows the Tokyo Subway system, with an easy drag-to-scroll feature. It's not that complex from an engineering standpoint, but a great idea nonetheless.

Check out the video

Pretty slick if you ask me. I'd love to be able to buy atlases for my portable system. Seems much more reasonable than carrying around a stack of paper.

Heck, MapQuest on the DS would be awesome. It could update it's maps and whatnot via the WiFi connection.

\\drew