Western developers like the DS

[A Black Falcon]

No, it couldn't. Look at what a DS cart looks like! It's a memory card! No way could that have anything added to it (as in something sticking out of the top of the cart like you can do with GB carts). That's why as I said Nintendo has also called the GBA port the 'expansion port'... the DS port can't handle the job.

Any DS tilt-sensor games, video/mp3/whatever addons, etc. will similarly have to use the GBA port. Though maybe with a DS card as well, who knows.

Oh, and OB1, what did this mean then, if not what I took it to?

What? How does Boktai for the GBA work? I don't understand your question.